docs: updated the license date

GCC 15 starts warning about non NUL-terminated string literals:

    chacha.c:44:31: error: initializer-string for array of ‘char’ truncates NUL terminator but destination lacks ‘nonstring’ attribute (17 chars into 16 available) [-Werror=unterminated-string-initialization]
       44 | static const char sigma[16] = "expand 32-byte k";
          |                               ^~~~~~~~~~~~~~~~~~

.clang-tidy

@@ -1,2 +1,2 @@
-Checks: 'bugprone-*,-bugprone-macro-parentheses,-bugprone-too-small-loop-variable,cert-*,clang-analyzer-*,-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,-clang-diagnostic-constant-logical-operand,readability-*,-readability-inconsistent-declaration-parameter-name,-readability-magic-numbers,-readability-named-parameter,llvm-include-order,misc-*'
+Checks: 'bugprone-*,-bugprone-easily-swappable-parameters,-bugprone-macro-parentheses,-bugprone-too-small-loop-variable,cert-*,-cert-err33-c,clang-analyzer-*,-clang-analyzer-security.insecureAPI.DeprecatedOrUnsafeBufferHandling,-clang-diagnostic-constant-logical-operand,readability-*,-readability-function-cognitive-complexity,-readability-identifier-length,-readability-inconsistent-declaration-parameter-name,-readability-magic-numbers,-readability-named-parameter,llvm-include-order,misc-*'
 WarningsAsErrors: '*'

.github/dependabot.yml

@@ -0,0 +1,7 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: daily
+    target-branch: main

.github/workflows/build-and-test.yml

@@ -0,0 +1,55 @@
+name: Build and run tests
+
+on:
+  push:
+  pull_request:
+  schedule:
+    - cron: '0 2 * * *'
+
+jobs:
+  build-ubuntu-gcc:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version: [12, 13, 14]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Setting up gcc version
+        run: |
+          sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-${{ matrix.version }} 100
+          sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-${{ matrix.version }} 100
+      - name: Build
+        run: make test
+  build-ubuntu-clang:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        version: [14, 15, 16, 17, 18]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y --no-install-recommends clang-14 clang-15
+      - name: Setting up clang version
+        run: |
+          sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-${{ matrix.version }} 100
+          sudo update-alternatives --install /usr/bin/clang clang /usr/bin/clang-${{ matrix.version }} 100
+      - name: Build
+        run: CC=clang CXX=clang++ make test
+  build-musl:
+    runs-on: ubuntu-latest
+    container:
+      image: alpine:latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: apk update && apk add build-base python3
+      - name: Build
+        run: make test
+  build-ubuntu-gcc-aarch64:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y --no-install-recommends gcc-aarch64-linux-gnu g++-aarch64-linux-gnu libgcc-s1-arm64-cross cpp-aarch64-linux-gnu
+      - name: Build
+        run: CC=aarch64-linux-gnu-gcc CXX=aarch64-linux-gnu-gcc++ make CONFIG_NATIVE=false

.gitignore

@@ -1,2 +1,2 @@
-*.o
-*.so
+out/
+out-light/

Android.bp

@@ -1,16 +1,13 @@
 common_cflags = [
+    "-pipe",
     "-O3",
     //"-flto",
     "-fPIC",
     "-fvisibility=hidden",
     //"-fno-plt",
-    "-pipe",
-    "-Wall",
-    "-Wextra",
     "-Wcast-align",
     "-Wcast-qual",
     "-Wwrite-strings",
-    "-Wno-constant-logical-operand",
     "-Werror",
     "-DH_MALLOC_PREFIX",
     "-DZERO_ON_FREE=true",
@@ -23,20 +20,21 @@ common_cflags = [
     "-DCONFIG_LARGE_SIZE_CLASSES=true",
     "-DGUARD_SLABS_INTERVAL=1",
     "-DGUARD_SIZE_DIVISOR=2",
-    "-DREGION_QUARANTINE_RANDOM_LENGTH=128",
+    "-DREGION_QUARANTINE_RANDOM_LENGTH=256",
     "-DREGION_QUARANTINE_QUEUE_LENGTH=1024",
     "-DREGION_QUARANTINE_SKIP_THRESHOLD=33554432", // 32MiB
     "-DFREE_SLABS_QUARANTINE_RANDOM_LENGTH=32",
-    "-DCONFIG_CLASS_REGION_SIZE=1073741824", // 1GiB
+    "-DCONFIG_CLASS_REGION_SIZE=34359738368", // 32GiB
     "-DN_ARENA=1",
     "-DCONFIG_STATS=true",
+    "-DCONFIG_SELF_INIT=false",
 ]
 
 cc_defaults {
     name: "hardened_malloc_defaults",
     defaults: ["linux_bionic_supported"],
     cflags: common_cflags,
-    conlyflags: ["-std=c11", "-Wmissing-prototypes"],
+    conlyflags: ["-std=c17", "-Wmissing-prototypes"],
     stl: "none",
 }
 
@@ -51,9 +49,13 @@ lib_src_files = [
 
 cc_library {
     name: "libhardened_malloc",
+    ramdisk_available: true,
+    vendor_ramdisk_available: true,
     recovery_available: true,
     defaults: ["hardened_malloc_defaults"],
     srcs: lib_src_files,
+    export_include_dirs: ["include"],
+    static_libs: ["libasync_safe"],
     target: {
         android: {
             shared: {
@@ -69,5 +71,11 @@ cc_library {
         debuggable: {
             cflags: ["-DLABEL_MEMORY"],
         },
+        device_has_arm_mte: {
+            cflags: ["-DHAS_ARM_MTE", "-march=armv8-a+dotprod+memtag"]
         },
+    },
+    apex_available: [
+        "com.android.runtime",
+    ],
 }

CREDITS

@@ -4,7 +4,7 @@ chacha.c is a simple conversion of chacha-merged.c to a keystream-only implement
     D. J. Bernstein
     Public domain.
 
-malloc.c open-addressed hash table (regions_grow, regions_insert, regions_find, regions_delete):
+h_malloc.c open-addressed hash table (regions_grow, regions_insert, regions_find, regions_delete):
 
     Copyright (c) 2008, 2010, 2011, 2016 Otto Moerbeek <otto@drijf.net>
     Copyright (c) 2012 Matthew Dempsky <matthew@openbsd.org>
@@ -54,3 +54,230 @@ libdivide:
 
 random.c get_random_{type}_uniform functions are based on Fast Random Integer
 Generation in an Interval by Daniel Lemire
+
+arm_mte.h arm_mte_tag_and_clear_mem function contents were copied from storeTags function in scudo:
+
+    ==============================================================================
+    The LLVM Project is under the Apache License v2.0 with LLVM Exceptions:
+    ==============================================================================
+
+                                     Apache License
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KERNEL_FEATURE_WISHLIST.md

@@ -16,6 +16,8 @@ Somewhat important and an easy sell:
     * also needed by jemalloc for different reasons
     * not needed if the kernel gets first class support for arbitrarily sized
       guard pages and a virtual memory quarantine feature
+    * `MREMAP_DONTUNMAP` is now available but doesn't support expanding the
+      mapping which may be an issue due to VMA merging being unreliable
 
 Fairly infeasible to land but could reduce overhead and extend coverage of
 security features to other code directly using mmap:

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2020 Daniel Micay
+Copyright © 2018-2025 GrapheneOS
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Makefile

@@ -1,38 +1,27 @@
-CONFIG_WERROR := true
-CONFIG_NATIVE := true
-CONFIG_CXX_ALLOCATOR := true
-CONFIG_UBSAN := false
-CONFIG_SEAL_METADATA := false
-CONFIG_ZERO_ON_FREE := true
-CONFIG_WRITE_AFTER_FREE_CHECK := true
-CONFIG_SLOT_RANDOMIZE := true
-CONFIG_SLAB_CANARY := true
-CONFIG_SLAB_QUARANTINE_RANDOM_LENGTH := 1
-CONFIG_SLAB_QUARANTINE_QUEUE_LENGTH := 1
-CONFIG_EXTENDED_SIZE_CLASSES := true
-CONFIG_LARGE_SIZE_CLASSES := true
-CONFIG_GUARD_SLABS_INTERVAL := 1
-CONFIG_GUARD_SIZE_DIVISOR := 2
-CONFIG_REGION_QUARANTINE_RANDOM_LENGTH := 128
-CONFIG_REGION_QUARANTINE_QUEUE_LENGTH := 1024
-CONFIG_REGION_QUARANTINE_SKIP_THRESHOLD := 33554432 # 32MiB
-CONFIG_FREE_SLABS_QUARANTINE_RANDOM_LENGTH := 32
-CONFIG_CLASS_REGION_SIZE := 34359738368 # 32GiB
-CONFIG_N_ARENA := 4
-CONFIG_STATS := false
+VARIANT := default
+
+ifneq ($(VARIANT),)
+    CONFIG_FILE := config/$(VARIANT).mk
+    include config/$(VARIANT).mk
+endif
+
+ifeq ($(VARIANT),default)
+    SUFFIX :=
+else
+    SUFFIX := -$(VARIANT)
+endif
+
+OUT := out$(SUFFIX)
 
 define safe_flag
-$(shell $(CC) $(if $(filter clang,$(CC)),-Werror=unknown-warning-option) -E $1 - </dev/null >/dev/null 2>&1 && echo $1 || echo $2)
+$(shell $(CC) $(if $(filter clang%,$(CC)),-Werror=unknown-warning-option) -E $1 - </dev/null >/dev/null 2>&1 && echo $1 || echo $2)
 endef
 
-CPPFLAGS := $(CPPFLAGS) -D_GNU_SOURCE
-SHARED_FLAGS := -O3 -flto -fPIC -fvisibility=hidden $(call safe_flag,-fno-plt) \
-    $(call safe_flag,-fstack-clash-protection) -fstack-protector-strong -pipe -Wall -Wextra \
-    $(call safe_flag,-Wcast-align=strict,-Wcast-align) -Wcast-qual -Wwrite-strings
-
-ifeq ($(CC),clang)
-    SHARED_FLAGS += -Wno-constant-logical-operand
-endif
+CPPFLAGS := $(CPPFLAGS) -D_GNU_SOURCE -I include
+SHARED_FLAGS := -pipe -O3 -flto -fPIC -fvisibility=hidden -fno-plt \
+    -fstack-clash-protection $(call safe_flag,-fcf-protection) -fstack-protector-strong \
+    -Wall -Wextra $(call safe_flag,-Wcast-align=strict,-Wcast-align) -Wcast-qual -Wwrite-strings \
+    -Wundef
 
 ifeq ($(CONFIG_WERROR),true)
     SHARED_FLAGS += -Werror
@@ -42,9 +31,13 @@ ifeq ($(CONFIG_NATIVE),true)
     SHARED_FLAGS += -march=native
 endif
 
-CFLAGS := $(CFLAGS) -std=c11 $(SHARED_FLAGS) -Wmissing-prototypes
-CXXFLAGS := $(CXXFLAGS) $(call safe_flag,-std=c++17,-std=c++14) $(SHARED_FLAGS)
-LDFLAGS := $(LDFLAGS) -Wl,--as-needed,-z,defs,-z,relro,-z,now,-z,nodlopen,-z,text
+ifeq ($(CONFIG_UBSAN),true)
+    SHARED_FLAGS += -fsanitize=undefined -fno-sanitize-recover=undefined
+endif
+
+CFLAGS := $(CFLAGS) -std=c17 $(SHARED_FLAGS) -Wmissing-prototypes -Wstrict-prototypes
+CXXFLAGS := $(CXXFLAGS) -std=c++17 -fsized-deallocation $(SHARED_FLAGS)
+LDFLAGS := $(LDFLAGS) -Wl,-O1,--as-needed,-z,defs,-z,relro,-z,now,-z,nodlopen,-z,text
 
 SOURCES := chacha.c h_malloc.c memory.c pages.c random.c util.c
 OBJECTS := $(SOURCES:.c=.o)
@@ -52,16 +45,13 @@ OBJECTS := $(SOURCES:.c=.o)
 ifeq ($(CONFIG_CXX_ALLOCATOR),true)
     # make sure LTO is compatible in case CC and CXX don't match (such as clang and g++)
     CXX := $(CC)
-    LDLIBS += -lstdc++ -lgcc_s
+    LDLIBS += -lstdc++
 
     SOURCES += new.cc
     OBJECTS += new.o
 endif
 
-ifeq ($(CONFIG_UBSAN),true)
-    CFLAGS += -fsanitize=undefined -fno-sanitize-recover=undefined
-    CXXFLAGS += -fsanitize=undefined -fno-sanitize-recover=undefined
-endif
+OBJECTS := $(addprefix $(OUT)/,$(OBJECTS))
 
 ifeq (,$(filter $(CONFIG_SEAL_METADATA),true false))
     $(error CONFIG_SEAL_METADATA must be true or false)
@@ -95,6 +85,10 @@ ifeq (,$(filter $(CONFIG_STATS),true false))
     $(error CONFIG_STATS must be true or false)
 endif
 
+ifeq (,$(filter $(CONFIG_SELF_INIT),true false))
+    $(error CONFIG_SELF_INIT must be true or false)
+endif
+
 CPPFLAGS += \
     -DCONFIG_SEAL_METADATA=$(CONFIG_SEAL_METADATA) \
     -DZERO_ON_FREE=$(CONFIG_ZERO_ON_FREE) \
@@ -113,29 +107,42 @@ CPPFLAGS += \
     -DFREE_SLABS_QUARANTINE_RANDOM_LENGTH=$(CONFIG_FREE_SLABS_QUARANTINE_RANDOM_LENGTH) \
     -DCONFIG_CLASS_REGION_SIZE=$(CONFIG_CLASS_REGION_SIZE) \
     -DN_ARENA=$(CONFIG_N_ARENA) \
-    -DCONFIG_STATS=$(CONFIG_STATS)
+    -DCONFIG_STATS=$(CONFIG_STATS) \
+    -DCONFIG_SELF_INIT=$(CONFIG_SELF_INIT)
 
-libhardened_malloc.so: $(OBJECTS)
+$(OUT)/libhardened_malloc$(SUFFIX).so: $(OBJECTS) | $(OUT)
 	$(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@
 
-chacha.o: chacha.c chacha.h util.h
-h_malloc.o: h_malloc.c h_malloc.h mutex.h memory.h pages.h random.h util.h
-memory.o: memory.c memory.h util.h
-new.o: new.cc h_malloc.h util.h
-pages.o: pages.c pages.h memory.h util.h
-random.o: random.c random.h chacha.h util.h
-util.o: util.c util.h
+$(OUT):
+	mkdir -p $(OUT)
+
+$(OUT)/chacha.o: chacha.c chacha.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
+$(OUT)/h_malloc.o: h_malloc.c include/h_malloc.h mutex.h memory.h pages.h random.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
+$(OUT)/memory.o: memory.c memory.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
+$(OUT)/new.o: new.cc include/h_malloc.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.cc) $(OUTPUT_OPTION) $<
+$(OUT)/pages.o: pages.c pages.h memory.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
+$(OUT)/random.o: random.c random.h chacha.h util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
+$(OUT)/util.o: util.c util.h $(CONFIG_FILE) | $(OUT)
+	$(COMPILE.c) $(OUTPUT_OPTION) $<
 
 check: tidy
 
 tidy:
-	clang-tidy $(SOURCES) -- $(CPPFLAGS)
+	clang-tidy --extra-arg=-std=c17 $(filter %.c,$(SOURCES)) -- $(CPPFLAGS)
+	clang-tidy --extra-arg=-std=c++17 $(filter %.cc,$(SOURCES)) -- $(CPPFLAGS)
 
 clean:
-	rm -f libhardened_malloc.so $(OBJECTS)
+	rm -f $(OUT)/libhardened_malloc.so $(OBJECTS)
+	$(MAKE) -C test/ clean
 
-test: libhardened_malloc.so
-	make -C test/
-	-python -m unittest discover --start-directory test/
+test: $(OUT)/libhardened_malloc$(SUFFIX).so
+	$(MAKE) -C test/
+	python3 -m unittest discover --start-directory test/
 
 .PHONY: check clean tidy test

README.md

@@ -32,7 +32,7 @@ to much less metadata overhead and memory waste from fragmentation than a more
 traditional allocator design. It aims to provide decent overall performance
 with a focus on long-term performance and memory usage rather than allocator
 micro-benchmarks. It offers scalability via a configurable number of entirely
-independently arenas, with the internal locking within arenas further divided
+independent arenas, with the internal locking within arenas further divided
 up per size class.
 
 This project currently supports Bionic (Android), musl and glibc. It may
@@ -65,12 +65,14 @@ used instead as this allocator fundamentally doesn't support that environment.
 
 ## Dependencies
 
-Debian stable (currently Debian 10) determines the most ancient set of
+Debian stable (currently Debian 12) determines the most ancient set of
 supported dependencies:
 
-* glibc 2.28
-* Linux 4.19
-* Clang 7.0 or GCC 8.3.0
+* glibc 2.36
+* Linux 6.1
+* Clang 14.0.6 or GCC 12.2.0
+
+For Android, the Linux GKI 5.10, 5.15 and 6.1 branches are supported.
 
 However, using more recent releases is highly recommended. Older versions of
 the dependencies may be compatible at the moment but are not tested and will
@@ -80,15 +82,8 @@ For external malloc replacement with musl, musl 1.1.20 is required. However,
 there will be custom integration offering better performance in the future
 along with other hardening for the C standard library implementation.
 
-For Android, only current generation Android Open Source Project branches will
-be supported, which currently means `android10-release`.
-
-The Linux kernel's implementation of Memory Protection Keys was severely broken
-before Linux 5.0. The `CONFIG_SEAL_METADATA` feature should only be enabled for
-use on kernels newer than 5.0 or longterm branches with a backport of the [fix
-for the
-issue](https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a31e184e4f69965c99c04cc5eb8a4920e0c63737).
-This issue was discovered and reported by the hardened\_malloc project.
+For Android, only the current generation, actively developed maintenance branch of the Android
+Open Source Project will be supported, which currently means `android15-release`.
 
 ## Testing
 
@@ -100,7 +95,7 @@ executables using glibc or musl:
     ./preload.sh krita --new-image RGBA,U8,500,500
 
 It can be necessary to substantially increase the `vm.max_map_count` sysctl to
-accomodate the large number of mappings caused by guard slabs and large
+accommodate the large number of mappings caused by guard slabs and large
 allocation guard regions. The number of mappings can also be drastically
 reduced via a significant increase to `CONFIG_GUARD_SLABS_INTERVAL` but the
 feature has a low performance and memory usage cost so that isn't recommended.
@@ -122,7 +117,8 @@ make command as follows:
 
 ## Compatibility
 
-OpenSSH 8.1 or higher is required to allow the mprotect PROT_READ|PROT_WRITE system calls in the seccomp-bpf filter rather than killing the process.
+OpenSSH 8.1 or higher is required to allow the mprotect `PROT_READ|PROT_WRITE`
+system calls in the seccomp-bpf filter rather than killing the process.
 
 ## OS integration
 
@@ -138,12 +134,12 @@ between performance and security. However, this reduces security for threat
 models where persistent state is untrusted, i.e. verified boot and attestation
 (see the [attestation sister project](https://attestation.app/about)).
 
-Make sure to raise `vm.max_map_count` substantially too to accomodate the very
+Make sure to raise `vm.max_map_count` substantially too to accommodate the very
 large number of guard pages created by hardened\_malloc. This can be done in
 `init.rc` (`system/core/rootdir/init.rc`) near the other virtual memory
 configuration:
 
-    write /proc/sys/vm/max_map_count 524240
+    write /proc/sys/vm/max_map_count 1048576
 
 This is unnecessary if you set `CONFIG_GUARD_SLABS_INTERVAL` to a very large
 value in the build configuration.
@@ -163,21 +159,31 @@ line to the `/etc/ld.so.preload` configuration file:
 The format of this configuration file is a whitespace-separated list, so it's
 good practice to put each library on a separate line.
 
+On Debian systems `libhardened_malloc.so` should be installed into `/usr/lib/`
+to avoid preload failures caused by AppArmor profile restrictions.
+
 Using the `LD_PRELOAD` environment variable to load it on a case-by-case basis
 will not work when `AT_SECURE` is set such as with setuid binaries. It's also
 generally not a recommended approach for production usage. The recommendation
 is to enable it globally and make exceptions for performance critical cases by
 running the application in a container / namespace without it enabled.
 
-Make sure to raise `vm.max_map_count` substantially too to accomodate the very
+Make sure to raise `vm.max_map_count` substantially too to accommodate the very
 large number of guard pages created by hardened\_malloc. As an example, in
 `/etc/sysctl.d/hardened_malloc.conf`:
 
-    vm.max_map_count = 524240
+    vm.max_map_count = 1048576
 
 This is unnecessary if you set `CONFIG_GUARD_SLABS_INTERVAL` to a very large
 value in the build configuration.
 
+On arm64, make sure your kernel is configured to use 4k pages since we haven't
+yet added support for 16k and 64k pages. The kernel also has to be configured
+to use 4 level page tables for the full 48 bit address space instead of only
+having a 39 bit address space for the default hardened\_malloc configuration.
+It's possible to reduce the class region size substantially to make a 39 bit
+address space workable but the defaults won't work.
+
 ## Configuration
 
 You can set some configuration options at compile-time via arguments to the
@@ -190,6 +196,30 @@ between portability, performance, memory usage or security. The core design
 choices are not configurable and the allocator remains very security-focused
 even with all the optional features disabled.
 
+The configuration system supports a configuration template system with two
+standard presets: the default configuration (`config/default.mk`) and a light
+configuration (`config/light.mk`). Packagers are strongly encouraged to ship
+both the standard `default` and `light` configuration. You can choose the
+configuration to build using `make VARIANT=light` where `make VARIANT=default`
+is the same as `make`. Non-default configuration templates will build a library
+with the suffix `-variant` such as `libhardened_malloc-light.so` and will use
+an `out-variant` directory instead of `out` for the build.
+
+The `default` configuration template has all normal optional security features
+enabled (just not the niche `CONFIG_SEAL_METADATA`) and is quite aggressive in
+terms of sacrificing performance and memory usage for security. The `light`
+configuration template disables the slab quarantines, write after free check,
+slot randomization and raises the guard slab interval from 1 to 8 but leaves
+zero-on-free and slab canaries enabled. The `light` configuration has solid
+performance and memory usage while still being far more secure than mainstream
+allocators with much better security properties. Disabling zero-on-free would
+gain more performance but doesn't make much difference for small allocations
+without also disabling slab canaries. Slab canaries slightly raise memory use
+and slightly slow down performance but are quite important to mitigate small
+overflows and C string overflows. Disabling slab canaries is not recommended
+in most cases since it would no longer be a strict upgrade over traditional
+allocators with headers on allocations and basic consistency checks for them.
+
 For reduced memory usage at the expense of performance (this will also reduce
 the size of the empty slab caches and quarantines, saving a lot of memory,
 since those are currently based on the size of the largest size class):
@@ -198,24 +228,6 @@ since those are currently based on the size of the largest size class):
     N_ARENA=1 \
     CONFIG_EXTENDED_SIZE_CLASSES=false
 
-The default configuration has all normal security features enabled (just not
-the niche `CONFIG_SEAL_METADATA`) and is quite aggressive in terms of
-sacrificing performance and memory usage for security. An example of a leaner
-configuration disabling expensive security features other than zero-on-free /
-slab canaries along with using far fewer guard slabs:
-
-    make \
-    CONFIG_WRITE_AFTER_FREE_CHECK=false \
-    CONFIG_SLOT_RANDOMIZE=false \
-    CONFIG_SLAB_QUARANTINE_RANDOM_LENGTH=0 \
-    CONFIG_SLAB_QUARANTINE_QUEUE_LENGTH=0 \
-    CONFIG_GUARD_SLABS_INTERVAL=8
-
-This is a more appropriate configuration for a more mainstream OS choosing to
-use hardened\_malloc while making a smaller memory and performance sacrifice.
-The slot randomization isn't particularly expensive but it's low value and is
-one of the first things to disable when aiming for higher performance.
-
 The following boolean configuration options are available:
 
 * `CONFIG_WERROR`: `true` (default) or `false` to control whether compiler
@@ -260,11 +272,10 @@ The following boolean configuration options are available:
 * `CONFIG_SEAL_METADATA`: `true` or `false` (default) to control whether Memory
   Protection Keys are used to disable access to all writable allocator state
   outside of the memory allocator code. It's currently disabled by default due
-  to lack of regular testing and a significant performance cost for this use
-  case on current generation hardware, which may become drastically lower in
-  the future. Whether or not this feature is enabled, the metadata is all
-  contained within an isolated memory region with high entropy random guard
-  regions around it.
+  to a significant performance cost for this use case on current generation
+  hardware, which may become drastically lower in the future. Whether or not
+  this feature is enabled, the metadata is all contained within an isolated
+  memory region with high entropy random guard regions around it.
 
 The following integer configuration options are available:
 
@@ -294,7 +305,7 @@ The following integer configuration options are available:
 * `CONFIG_GUARD_SIZE_DIVISOR`: `2` (default) to control the maximum size of the
   guard regions placed on both sides of large memory allocations, relative to
   the usable size of the memory allocation.
-* `CONFIG_REGION_QUARANTINE_RANDOM_LENGTH`: `128` (default) to control the
+* `CONFIG_REGION_QUARANTINE_RANDOM_LENGTH`: `256` (default) to control the
   number of slots in the random array used to randomize region reuse for large
   memory allocations.
 * `CONFIG_REGION_QUARANTINE_QUEUE_LENGTH`: `1024` (default) to control the
@@ -462,16 +473,16 @@ was a bit less important and if a core goal was finding latent bugs.
     * Errors other than ENOMEM from mmap, munmap, mprotect and mremap treated
       as fatal, which can help to detect memory management gone wrong elsewhere
       in the process.
-* [future] Memory tagging for slab allocations via MTE on ARMv8.5+
+* Memory tagging for slab allocations via MTE on ARMv8.5+
     * random memory tags as the baseline, providing probabilistic protection
       against various forms of memory corruption
     * dedicated tag for free slots, set on free, for deterministic protection
       against accessing freed memory
-    * store previous random tag within freed slab allocations, and increment it
-      to get the next tag for that slot to provide deterministic use-after-free
-      detection through multiple cycles of memory reuse
     * guarantee distinct tags for adjacent memory allocations by incrementing
       past matching values for deterministic detection of linear overflows
+    * [future] store previous random tag and increment it to get the next tag
+      for that slot to provide deterministic use-after-free detection through
+      multiple cycles of memory reuse
 
 ## Randomness
 
@@ -494,7 +505,7 @@ ChaCha8 is a great fit because it's extremely fast across platforms without
 relying on hardware support or complex platform-specific code. The security
 margins of ChaCha20 would be completely overkill for the use case. Using
 ChaCha8 avoids needing to resort to a non-cryptographically secure PRNG or
-something without a lot of scrunity. The current implementation is simply the
+something without a lot of scrutiny. The current implementation is simply the
 reference implementation of ChaCha8 converted into a pure keystream by ripping
 out the XOR of the message into the keystream.
 
@@ -588,10 +599,10 @@ retaining the isolation.
 
 | size class | worst case internal fragmentation | slab slots | slab size | internal fragmentation for slabs |
 | - | - | - | - | - |
-| 20480 | 20.0% | 2 | 40960 | 0.0% |
-| 24576 | 16.66% | 2 | 49152 | 0.0% |
-| 28672 | 14.28% | 2 | 57344 | 0.0% |
-| 32768 | 12.5% | 2 | 65536 | 0.0% |
+| 20480 | 20.0% | 1 | 20480 | 0.0% |
+| 24576 | 16.66% | 1 | 24576 | 0.0% |
+| 28672 | 14.28% | 1 | 28672 | 0.0% |
+| 32768 | 12.5% | 1 | 32768 | 0.0% |
 | 40960 | 20.0% | 1 | 40960 | 0.0% |
 | 49152 | 16.66% | 1 | 49152 | 0.0% |
 | 57344 | 14.28% | 1 | 57344 | 0.0% |
@@ -713,77 +724,46 @@ freeing as there would be if the kernel supported these features directly.
 
 ## Memory tagging
 
-Integrating extensive support for ARMv8.5 memory tagging is planned and this
-section will be expanded cover the details on the chosen design. The approach
-for slab allocations is currently covered, but it can also be used for the
-allocator metadata region and large allocations.
+Random tags are set for all slab allocations when allocated, with 4 excluded values:
 
-Memory allocations are already always multiples of naturally aligned 16 byte
-units, so memory tags are a natural fit into a malloc implementation due to the
-16 byte alignment requirement. The only extra memory consumption will come from
-the hardware supported storage for the tag values (4 bits per 16 bytes).
+1. the reserved `0` tag
+2. the previous tag used for the slot
+3. the current (or previous) tag used for the slot to the left
+4. the current (or previous) tag used for the slot to the right
 
-The baseline policy will be to generate random tags for each slab allocation
-slot on first use. The highest value will be reserved for marking freed memory
-allocations to detect any accesses to freed memory so it won't be part of the
-generated range. Adjacent slots will be guaranteed to have distinct memory tags
-in order to guarantee that linear overflows are detected. There are a few ways
-of implementing this and it will end up depending on the performance costs of
-different approaches. If there's an efficient way to fetch the adjacent tag
-values without wasting extra memory, it will be possible to check for them and
-skip them either by generating a new random value in a loop or incrementing
-past them since the tiny bit of bias wouldn't matter. Another approach would be
-alternating odd and even tag values but that would substantially reduce the
-overall randomness of the tags and there's very little entropy from the start.
+When a slab allocation is freed, the reserved `0` tag is set for the slot.
+Slab allocation slots are cleared before reuse when memory tagging is enabled.
 
-Once a slab allocation has been freed, the tag will be set to the reserved
-value for free memory and the previous tag value will be stored inside the
-allocation itself. The next time the slot is allocated, the chosen tag value
-will be the previous value incremented by one to provide use-after-free
-detection between generations of allocations. The stored tag will be wiped
-before retagging the memory, to avoid leaking it and as part of preserving the
-security property of newly allocated memory being zeroed due to zero-on-free.
-It will eventually wrap all the way around, but this ends up providing a strong
-guarantee for many allocation cycles due to the combination of 4 bit tags with
-the FIFO quarantine feature providing delayed free. It also benefits from
-random slot allocation and the randomized portion of delayed free, which result
-in a further delay along with preventing a deterministic bypass by forcing a
-reuse after a certain number of allocation cycles. Similarly to the initial tag
-generation, tag values for adjacent allocations will be skipped by incrementing
-past them.
+This ensures the following properties:
 
-For example, consider this slab of allocations that are not yet used with 15
-representing the tag for free memory. For the sake of simplicity, there will be
-no quarantine or other slabs for this example:
+- Linear overflows are deterministically detected.
+- Use-after-free are deterministically detected until the freed slot goes through
+  both the random and FIFO quarantines, gets allocated again, goes through both
+  quarantines again and then finally gets allocated again for a 2nd time.
+- Since the default `0` tag is reserved, untagged pointers can't access slab
+  allocations and vice versa.
 
-    | 15 | 15 | 15 | 15 | 15 | 15 |
+Slab allocations are done in a statically reserved region for each size class
+and all metadata is in a statically reserved region, so interactions between
+different uses of the same address space is not applicable.
 
-Three slots are randomly chosen for allocations, with random tags assigned (2,
-7, 14) since these slots haven't ever been used and don't have saved values:
+Large allocations beyond the largest slab allocation size class (128k by
+default) are guaranteed to have randomly sized guard regions to the left and
+right. Random and FIFO address space quarantines provide use-after-free
+detection. We need to test whether the cost of random tags is acceptable to enabled them by default,
+since they would be useful for:
 
-    | 15 | 2  | 15 | 7  | 14 | 15 |
+- probabilistic detection of overflows
+- probabilistic detection of use-after-free once the address space is
+  out of the quarantine and reused for another allocation
+- deterministic detection of use-after-free for reuse by another allocator.
 
-The 2nd allocation slot is freed, and is set back to the tag for free memory
-(15), but with the previous tag value stored in the freed space:
-
-    | 15 | 15 | 15 | 7  | 14 | 15 |
-
-The first slot is allocated for the first time, receiving the random value 3:
-
-    | 3  | 15 | 15 | 7  | 14 | 15 |
-
-The 2nd slot is randomly chosen again, so the previous tag (2) is retrieved and
-incremented to 3 as part of the use-after-free mitigation. An adjacent
-allocation already uses the tag 3, so the tag is further incremented to 4 (it
-would be incremented to 5 if one of the adjacent tags was 4):
-
-    | 3  | 4  | 15 | 7  | 14 | 15 |
-
-The last slot is randomly chosen for the next alocation, and is assigned the
-random value 14. However, it's placed next to an allocation with the tag 14 so
-the tag is incremented and wraps around to 0:
-
-    | 3  | 4  | 15 | 7  | 14 | 0  |
+When memory tagging is enabled, checking for write-after-free at allocation
+time and checking canaries are both disabled. Canaries will be more thoroughly
+disabled when using memory tagging in the future, but Android currently has
+[very dynamic memory tagging support](https://source.android.com/docs/security/test/memory-safety/arm-mte)
+where it can be disabled at any time which creates a barrier to optimizing
+by disabling redundant features.
 
 ## API extensions
 
@@ -835,7 +815,7 @@ is still provided, with a similar format as what Android uses, with tweaks for
 hardened\_malloc and the version set to `hardened_malloc-1`. The data format
 may be changed in the future.
 
-As an example, consider the follow program from the hardened\_malloc tests:
+As an example, consider the following program from the hardened\_malloc tests:
 
 ```c
 #include <pthread.h>
@@ -986,6 +966,9 @@ number to the corresponding size class. The bin index begins at 0, mapping to
 the 0 byte size class, followed by 1 for the 16 bytes, 2 for 32 bytes, etc. and
 large allocations are treated as one group.
 
+When stats aren't enabled, the `malloc_info` output will be an empty `malloc`
+element.
+
 ## System calls
 
 This is intended to aid with creating system call whitelists via seccomp-bpf
@@ -1004,6 +987,7 @@ System calls used by all build configurations:
 * `mremap(old, old_size, new_size, MREMAP_MAYMOVE|MREMAP_FIXED, new)`
 * `munmap`
 * `write(STDERR_FILENO, buf, len)` (before aborting due to memory corruption)
+* `madvise(ptr, size, MADV_DONTNEED)`
 
 The main distinction from a typical malloc implementation is the use of
 getrandom. A common compatibility issue is that existing system call whitelists

androidtest/Android.bp

@@ -0,0 +1,25 @@
+java_test_host {
+    name: "HMallocTest",
+    srcs: [
+        "src/**/*.java",
+    ],
+
+    libs: [
+        "tradefed",
+        "compatibility-tradefed",
+        "compatibility-host-util",
+    ],
+
+    static_libs: [
+        "cts-host-utils",
+        "frameworks-base-hostutils",
+    ],
+
+    test_suites: [
+        "general-tests",
+    ],
+
+    data_device_bins_64: [
+        "memtag_test",
+    ],
+}

androidtest/AndroidTest.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<configuration description="hardened_malloc test">
+
+    <target_preparer class="com.android.compatibility.common.tradefed.targetprep.FilePusher">
+        <option name="cleanup" value="true" />
+        <option name="push" value="memtag_test->/data/local/tmp/memtag_test" />
+    </target_preparer>
+
+    <test class="com.android.compatibility.common.tradefed.testtype.JarHostTest" >
+        <option name="jar" value="HMallocTest.jar" />
+    </test>
+
+</configuration>

androidtest/memtag/Android.bp

@@ -0,0 +1,17 @@
+cc_test {
+    name: "memtag_test",
+    srcs: ["memtag_test.cc"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+        "-Wextra",
+        "-O0",
+        "-march=armv9-a+memtag",
+    ],
+
+    compile_multilib: "64",
+
+    sanitize: {
+        memtag_heap: true,
+    },
+}

androidtest/memtag/memtag_test.cc

@@ -0,0 +1,351 @@
+// needed to uncondionally enable assertions
+#undef NDEBUG
+#include <assert.h>
+#include <malloc.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/utsname.h>
+#include <unistd.h>
+
+#include <map>
+#include <set>
+#include <string>
+#include <unordered_map>
+
+#include "../../arm_mte.h"
+
+using namespace std;
+
+using u8 = uint8_t;
+using uptr = uintptr_t;
+using u64 = uint64_t;
+
+const size_t DEFAULT_ALLOC_SIZE = 8;
+const size_t CANARY_SIZE = 8;
+
+void do_context_switch() {
+    utsname s;
+    uname(&s);
+}
+
+u8 get_pointer_tag(void *ptr) {
+    return (((uptr) ptr) >> 56) & 0xf;
+}
+
+void *untag_pointer(void *ptr) {
+    const uintptr_t mask = UINTPTR_MAX >> 8;
+    return (void *) ((uintptr_t) ptr & mask);
+}
+
+void *set_pointer_tag(void *ptr, u8 tag) {
+    return (void *) (((uintptr_t) tag << 56) | (uintptr_t) untag_pointer(ptr));
+}
+
+// This test checks that slab slot allocation uses tag that is distint from tags of its neighbors
+// and from the tag of the previous allocation that used the same slot
+void tag_distinctness() {
+    // tag 0 is reserved
+    const int min_tag = 1;
+    const int max_tag = 0xf;
+
+    struct SizeClass {
+        int size;
+        int slot_cnt;
+    };
+
+    // values from size_classes[] and size_class_slots[] in h_malloc.c
+    SizeClass size_classes[] = {
+        { .size = 16,    .slot_cnt = 256, },
+        { .size = 32,    .slot_cnt = 128, },
+        // this size class is used by allocations that are made by the addr_tag_map, which breaks
+        // tag distinctess checks
+        // { .size = 48,    .slot_cnt = 85,  },
+        { .size = 64,    .slot_cnt = 64,  },
+        { .size = 80,    .slot_cnt = 51,  },
+        { .size = 96,    .slot_cnt = 42,  },
+        { .size = 112,   .slot_cnt = 36,  },
+        { .size = 128,   .slot_cnt = 64,  },
+        { .size = 160,   .slot_cnt = 51,  },
+        { .size = 192,   .slot_cnt = 64,  },
+        { .size = 224,   .slot_cnt = 54,  },
+        { .size = 10240, .slot_cnt = 6,   },
+        { .size = 20480, .slot_cnt = 1,   },
+    };
+
+    int tag_usage[max_tag + 1];
+
+    for (size_t sc_idx = 0; sc_idx < sizeof(size_classes) / sizeof(SizeClass); ++sc_idx) {
+        SizeClass &sc = size_classes[sc_idx];
+
+        const size_t full_alloc_size = sc.size;
+        const size_t alloc_size = full_alloc_size - CANARY_SIZE;
+
+        // "tdc" is short for "tag distinctness check"
+        int left_neighbor_tdc_cnt = 0;
+        int right_neighbor_tdc_cnt = 0;
+        int prev_alloc_tdc_cnt = 0;
+
+        int iter_cnt = 600;
+
+        unordered_map<uptr, u8> addr_tag_map;
+        addr_tag_map.reserve(iter_cnt * sc.slot_cnt);
+
+        u64 seen_tags = 0;
+
+        for (int iter = 0; iter < iter_cnt; ++iter) {
+            uptr allocations[256]; // 256 is max slot count
+
+            for (int i = 0; i < sc.slot_cnt; ++i) {
+                u8 *p = (u8 *) malloc(alloc_size);
+                assert(p);
+                uptr addr = (uptr) untag_pointer(p);
+                u8 tag = get_pointer_tag(p);
+
+                assert(tag >= min_tag && tag <= max_tag);
+                seen_tags |= 1 << tag;
+                ++tag_usage[tag];
+
+                // check most recent tags of left and right neighbors
+
+                auto left = addr_tag_map.find(addr - full_alloc_size);
+                if (left != addr_tag_map.end()) {
+                    assert(left->second != tag);
+                    ++left_neighbor_tdc_cnt;
+                }
+
+                auto right = addr_tag_map.find(addr + full_alloc_size);
+                if (right != addr_tag_map.end()) {
+                    assert(right->second != tag);
+                    ++right_neighbor_tdc_cnt;
+                }
+
+                // check previous tag of this slot
+                auto prev = addr_tag_map.find(addr);
+                if (prev != addr_tag_map.end()) {
+                    assert(prev->second != tag);
+                    ++prev_alloc_tdc_cnt;
+                    addr_tag_map.erase(addr);
+                }
+
+                addr_tag_map.emplace(addr, tag);
+
+                for (size_t j = 0; j < alloc_size; ++j) {
+                    // check that slot is zeroed
+                    assert(p[j] == 0);
+                    // check that slot is readable and writable
+                    p[j]++;
+                }
+
+                allocations[i] = addr;
+            }
+
+            // free some of allocations to allow their slots to be reused
+            for (int i = sc.slot_cnt - 1; i >= 0; i -= 2) {
+                free((void *) allocations[i]);
+            }
+        }
+
+        // check that all of the tags were used, except for the reserved tag 0
+        assert(seen_tags == (0xffff & ~(1 << 0)));
+
+        printf("size_class\t%i\t" "tdc_left %i\t" "tdc_right %i\t" "tdc_prev_alloc %i\n",
+               sc.size, left_neighbor_tdc_cnt, right_neighbor_tdc_cnt, prev_alloc_tdc_cnt);
+
+        // make sure tag distinctess checks were actually performed
+        int min_tdc_cnt = sc.slot_cnt * iter_cnt / 5;
+
+        assert(prev_alloc_tdc_cnt > min_tdc_cnt);
+
+        if (sc.slot_cnt > 1) {
+            assert(left_neighbor_tdc_cnt > min_tdc_cnt);
+            assert(right_neighbor_tdc_cnt > min_tdc_cnt);
+        }
+
+        // async tag check failures are reported on context switch
+        do_context_switch();
+    }
+
+    printf("\nTag use counters:\n");
+
+    int min = INT_MAX;
+    int max = 0;
+    double geomean = 0.0;
+    for (int i = min_tag; i <= max_tag; ++i) {
+        int v = tag_usage[i];
+        geomean += log(v);
+        min = std::min(min, v);
+        max = std::max(max, v);
+        printf("%i\t%i\n", i, tag_usage[i]);
+    }
+    int tag_cnt = 1 + max_tag - min_tag;
+    geomean = exp(geomean / tag_cnt);
+
+    double max_deviation = std::max((double) max - geomean, geomean - min);
+
+    printf("geomean: %.2f, max deviation from geomean: %.2f%%\n", geomean, (100.0 * max_deviation) / geomean);
+}
+
+u8* alloc_default() {
+    const size_t full_alloc_size = DEFAULT_ALLOC_SIZE + CANARY_SIZE;
+    set<uptr> addrs;
+
+    // make sure allocation has both left and right neighbors, otherwise overflow/underflow tests
+    // will fail when allocation is at the end/beginning of slab
+    for (;;) {
+        u8 *p = (u8 *) malloc(DEFAULT_ALLOC_SIZE);
+        assert(p);
+
+        uptr addr = (uptr) untag_pointer(p);
+        uptr left = addr - full_alloc_size;
+        if (addrs.find(left) != addrs.end()) {
+            uptr right = addr + full_alloc_size;
+            if (addrs.find(right) != addrs.end()) {
+                return p;
+            }
+        }
+
+        addrs.emplace(addr);
+    }
+}
+
+int expected_segv_code;
+
+#define expect_segv(exp, segv_code) ({\
+    expected_segv_code = segv_code; \
+    volatile auto val = exp; \
+    (void) val; \
+    do_context_switch(); \
+    fprintf(stderr, "didn't receive SEGV code %i", segv_code); \
+    exit(1); })
+
+// it's expected that the device is configured to use asymm MTE tag checking mode (sync read checks,
+// async write checks)
+#define expect_read_segv(exp) expect_segv(exp, SEGV_MTESERR)
+#define expect_write_segv(exp) expect_segv(exp, SEGV_MTEAERR)
+
+void read_after_free() {
+    u8 *p = alloc_default();
+    free(p);
+    expect_read_segv(p[0]);
+}
+
+void write_after_free() {
+    u8 *p = alloc_default();
+    free(p);
+    expect_write_segv(p[0] = 1);
+}
+
+void underflow_read() {
+    u8 *p = alloc_default();
+    expect_read_segv(p[-1]);
+}
+
+void underflow_write() {
+    u8 *p = alloc_default();
+    expect_write_segv(p[-1] = 1);
+}
+
+void overflow_read() {
+    u8 *p = alloc_default();
+    expect_read_segv(p[DEFAULT_ALLOC_SIZE + CANARY_SIZE]);
+}
+
+void overflow_write() {
+    u8 *p = alloc_default();
+    expect_write_segv(p[DEFAULT_ALLOC_SIZE + CANARY_SIZE] = 1);
+}
+
+void untagged_read() {
+    u8 *p = alloc_default();
+    p = (u8 *) untag_pointer(p);
+    expect_read_segv(p[0]);
+}
+
+void untagged_write() {
+    u8 *p = alloc_default();
+    p = (u8 *) untag_pointer(p);
+    expect_write_segv(p[0] = 1);
+}
+
+// checks that each of memory locations inside the buffer is tagged with expected_tag
+void check_tag(void *buf, size_t len, u8 expected_tag) {
+    for (size_t i = 0; i < len; ++i) {
+        assert(get_pointer_tag(__arm_mte_get_tag((void *) ((uintptr_t) buf + i))) == expected_tag);
+    }
+}
+
+void madvise_dontneed() {
+    const size_t len = 100'000;
+    void *ptr = mmap(NULL, len, PROT_READ | PROT_WRITE | PROT_MTE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+    assert(ptr != MAP_FAILED);
+
+    // check that 0 is the initial tag
+    check_tag(ptr, len, 0);
+
+    arm_mte_tag_and_clear_mem(set_pointer_tag(ptr, 1), len);
+    check_tag(ptr, len, 1);
+
+    memset(set_pointer_tag(ptr, 1), 1, len);
+
+    assert(madvise(ptr, len, MADV_DONTNEED) == 0);
+    // check that MADV_DONTNEED resets the tag
+    check_tag(ptr, len, 0);
+
+    // check that MADV_DONTNEED clears the memory
+    for (size_t i = 0; i < len; ++i) {
+        assert(((u8 *) ptr)[i] == 0);
+    }
+
+    // check that mistagged read after MADV_DONTNEED fails
+    expect_read_segv(*((u8 *) set_pointer_tag(ptr, 1)));
+}
+
+map<string, function<void()>> tests = {
+#define TEST(s) { #s, s }
+    TEST(tag_distinctness),
+    TEST(read_after_free),
+    TEST(write_after_free),
+    TEST(overflow_read),
+    TEST(overflow_write),
+    TEST(underflow_read),
+    TEST(underflow_write),
+    TEST(untagged_read),
+    TEST(untagged_write),
+    TEST(madvise_dontneed),
+#undef TEST
+};
+
+void segv_handler(int, siginfo_t *si, void *) {
+    if (expected_segv_code == 0 || expected_segv_code != si->si_code) {
+        fprintf(stderr, "received unexpected SEGV_CODE %i", si->si_code);
+        exit(139); // standard exit code for SIGSEGV
+    }
+
+    exit(0);
+}
+
+int main(int argc, char **argv) {
+    setbuf(stdout, NULL);
+    assert(argc == 2);
+
+    auto test_name = string(argv[1]);
+    auto test_fn = tests[test_name];
+    assert(test_fn != nullptr);
+
+    assert(mallopt(M_BIONIC_SET_HEAP_TAGGING_LEVEL, M_HEAP_TAGGING_LEVEL_ASYNC) == 1);
+
+    struct sigaction sa = {
+        .sa_sigaction = segv_handler,
+        .sa_flags = SA_SIGINFO,
+    };
+
+    assert(sigaction(SIGSEGV, &sa, nullptr) == 0);
+
+    test_fn();
+    do_context_switch();
+
+    return 0;
+}

androidtest/src/grapheneos/hmalloc/MemtagTest.java

@@ -0,0 +1,79 @@
+package grapheneos.hmalloc;
+
+import com.android.tradefed.device.DeviceNotAvailableException;
+import com.android.tradefed.testtype.DeviceJUnit4ClassRunner;
+import com.android.tradefed.testtype.junit4.BaseHostJUnit4Test;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+import java.util.ArrayList;
+
+import static org.junit.Assert.assertEquals;
+
+@RunWith(DeviceJUnit4ClassRunner.class)
+public class MemtagTest extends BaseHostJUnit4Test {
+    private static final String TEST_BINARY = "/data/local/tmp/memtag_test";
+
+    private void runTest(String name) throws DeviceNotAvailableException {
+        var args = new ArrayList<String>();
+        args.add(TEST_BINARY);
+        args.add(name);
+        String cmdLine = String.join(" ", args);
+
+        var result = getDevice().executeShellV2Command(cmdLine);
+
+        assertEquals("stderr", "", result.getStderr());
+        assertEquals("process exit code", 0, result.getExitCode().intValue());
+    }
+
+    @Test
+    public void tag_distinctness() throws DeviceNotAvailableException {
+        runTest("tag_distinctness");
+    }
+
+    @Test
+    public void read_after_free() throws DeviceNotAvailableException {
+        runTest("read_after_free");
+    }
+
+    @Test
+    public void write_after_free() throws DeviceNotAvailableException {
+        runTest("write_after_free");
+    }
+
+    @Test
+    public void underflow_read() throws DeviceNotAvailableException {
+        runTest("underflow_read");
+    }
+
+    @Test
+    public void underflow_write() throws DeviceNotAvailableException {
+        runTest("underflow_write");
+    }
+
+    @Test
+    public void overflow_read() throws DeviceNotAvailableException {
+        runTest("overflow_read");
+    }
+
+    @Test
+    public void overflow_write() throws DeviceNotAvailableException {
+        runTest("overflow_write");
+    }
+
+    @Test
+    public void untagged_read() throws DeviceNotAvailableException {
+        runTest("untagged_read");
+    }
+
+    @Test
+    public void untagged_write() throws DeviceNotAvailableException {
+        runTest("untagged_write");
+    }
+
+    @Test
+    public void madvise_dontneed() throws DeviceNotAvailableException {
+        runTest("madvise_dontneed");
+    }
+}

arm_mte.h

@@ -0,0 +1,91 @@
+#ifndef ARM_MTE_H
+#define ARM_MTE_H
+
+#include <arm_acle.h>
+#include <stdint.h>
+
+// Returns a tagged pointer.
+// See https://developer.arm.com/documentation/ddi0602/2023-09/Base-Instructions/IRG--Insert-Random-Tag-
+static inline void *arm_mte_create_random_tag(void *p, uint64_t exclusion_mask) {
+    return __arm_mte_create_random_tag(p, exclusion_mask);
+}
+
+// Tag the memory region with the tag specified in tag bits of tagged_ptr. Memory region itself is
+// zeroed.
+// tagged_ptr has to be aligned by 16, and len has to be a multiple of 16 (tag granule size).
+//
+// Arm's software optimization guide says:
+// "it is recommended to use STZGM (or DCZGVA) to set tag if data is not a concern." (STZGM and
+// DCGZVA are zeroing variants of tagging instructions).
+//
+// Contents of this function were copied from scudo:
+// https://android.googlesource.com/platform/external/scudo/+/refs/tags/android-14.0.0_r1/standalone/memtag.h#167
+//
+// scudo is licensed under the Apache License v2.0 with LLVM Exceptions, which is compatible with
+// the hardened_malloc's MIT license
+static inline void arm_mte_tag_and_clear_mem(void *tagged_ptr, size_t len) {
+    uintptr_t Begin = (uintptr_t) tagged_ptr;
+    uintptr_t End = Begin + len;
+    uintptr_t LineSize, Next, Tmp;
+    __asm__ __volatile__(
+        ".arch_extension memtag \n\t"
+
+        // Compute the cache line size in bytes (DCZID_EL0 stores it as the log2
+        // of the number of 4-byte words) and bail out to the slow path if DCZID_EL0
+        // indicates that the DC instructions are unavailable.
+        "DCZID .req %[Tmp] \n\t"
+        "mrs DCZID, dczid_el0 \n\t"
+        "tbnz DCZID, #4, 3f \n\t"
+        "and DCZID, DCZID, #15 \n\t"
+        "mov %[LineSize], #4 \n\t"
+        "lsl %[LineSize], %[LineSize], DCZID \n\t"
+        ".unreq DCZID \n\t"
+
+        // Our main loop doesn't handle the case where we don't need to perform any
+        // DC GZVA operations. If the size of our tagged region is less than
+        // twice the cache line size, bail out to the slow path since it's not
+        // guaranteed that we'll be able to do a DC GZVA.
+        "Size .req %[Tmp] \n\t"
+        "sub Size, %[End], %[Cur] \n\t"
+        "cmp Size, %[LineSize], lsl #1 \n\t"
+        "b.lt 3f \n\t"
+        ".unreq Size \n\t"
+
+        "LineMask .req %[Tmp] \n\t"
+        "sub LineMask, %[LineSize], #1 \n\t"
+
+        // STZG until the start of the next cache line.
+        "orr %[Next], %[Cur], LineMask \n\t"
+
+        "1:\n\t"
+        "stzg %[Cur], [%[Cur]], #16 \n\t"
+        "cmp %[Cur], %[Next] \n\t"
+        "b.lt 1b \n\t"
+
+        // DC GZVA cache lines until we have no more full cache lines.
+        "bic %[Next], %[End], LineMask \n\t"
+        ".unreq LineMask \n\t"
+
+        "2: \n\t"
+        "dc gzva, %[Cur] \n\t"
+        "add %[Cur], %[Cur], %[LineSize] \n\t"
+        "cmp %[Cur], %[Next] \n\t"
+        "b.lt 2b \n\t"
+
+        // STZG until the end of the tagged region. This loop is also used to handle
+        // slow path cases.
+
+        "3: \n\t"
+        "cmp %[Cur], %[End] \n\t"
+        "b.ge 4f \n\t"
+        "stzg %[Cur], [%[Cur]], #16 \n\t"
+        "b 3b \n\t"
+
+        "4: \n\t"
+
+        : [Cur] "+&r"(Begin), [LineSize] "=&r"(LineSize), [Next] "=&r"(Next), [Tmp] "=&r"(Tmp)
+        : [End] "r"(End)
+        : "memory"
+    );
+}
+#endif

chacha.c

@@ -41,7 +41,7 @@ static const unsigned rounds = 8;
     a = PLUS(a, b); d = ROTATE(XOR(d, a), 8); \
     c = PLUS(c, d); b = ROTATE(XOR(b, c), 7);
 
-static const char sigma[16] = "expand 32-byte k";
+static const char sigma[16] NONSTRING = "expand 32-byte k";
 
 void chacha_keysetup(chacha_ctx *x, const u8 *k) {
     x->input[0] = U8TO32_LITTLE(sigma + 0);

config/default.mk

@@ -0,0 +1,23 @@
+CONFIG_WERROR := true
+CONFIG_NATIVE := true
+CONFIG_CXX_ALLOCATOR := true
+CONFIG_UBSAN := false
+CONFIG_SEAL_METADATA := false
+CONFIG_ZERO_ON_FREE := true
+CONFIG_WRITE_AFTER_FREE_CHECK := true
+CONFIG_SLOT_RANDOMIZE := true
+CONFIG_SLAB_CANARY := true
+CONFIG_SLAB_QUARANTINE_RANDOM_LENGTH := 1
+CONFIG_SLAB_QUARANTINE_QUEUE_LENGTH := 1
+CONFIG_EXTENDED_SIZE_CLASSES := true
+CONFIG_LARGE_SIZE_CLASSES := true
+CONFIG_GUARD_SLABS_INTERVAL := 1
+CONFIG_GUARD_SIZE_DIVISOR := 2
+CONFIG_REGION_QUARANTINE_RANDOM_LENGTH := 256
+CONFIG_REGION_QUARANTINE_QUEUE_LENGTH := 1024
+CONFIG_REGION_QUARANTINE_SKIP_THRESHOLD := 33554432 # 32MiB
+CONFIG_FREE_SLABS_QUARANTINE_RANDOM_LENGTH := 32
+CONFIG_CLASS_REGION_SIZE := 34359738368 # 32GiB
+CONFIG_N_ARENA := 4
+CONFIG_STATS := false
+CONFIG_SELF_INIT := true

config/light.mk

@@ -0,0 +1,23 @@
+CONFIG_WERROR := true
+CONFIG_NATIVE := true
+CONFIG_CXX_ALLOCATOR := true
+CONFIG_UBSAN := false
+CONFIG_SEAL_METADATA := false
+CONFIG_ZERO_ON_FREE := true
+CONFIG_WRITE_AFTER_FREE_CHECK := false
+CONFIG_SLOT_RANDOMIZE := false
+CONFIG_SLAB_CANARY := true
+CONFIG_SLAB_QUARANTINE_RANDOM_LENGTH := 0
+CONFIG_SLAB_QUARANTINE_QUEUE_LENGTH := 0
+CONFIG_EXTENDED_SIZE_CLASSES := true
+CONFIG_LARGE_SIZE_CLASSES := true
+CONFIG_GUARD_SLABS_INTERVAL := 8
+CONFIG_GUARD_SIZE_DIVISOR := 2
+CONFIG_REGION_QUARANTINE_RANDOM_LENGTH := 256
+CONFIG_REGION_QUARANTINE_QUEUE_LENGTH := 1024
+CONFIG_REGION_QUARANTINE_SKIP_THRESHOLD := 33554432 # 32MiB
+CONFIG_FREE_SLABS_QUARANTINE_RANDOM_LENGTH := 32
+CONFIG_CLASS_REGION_SIZE := 34359738368 # 32GiB
+CONFIG_N_ARENA := 4
+CONFIG_STATS := false
+CONFIG_SELF_INIT := true

include/h_malloc.h

@@ -23,6 +23,7 @@ extern "C" {
 #define h_malloc_trim malloc_trim
 #define h_malloc_stats malloc_stats
 #define h_mallinfo mallinfo
+#define h_mallinfo2 mallinfo2
 #define h_malloc_info malloc_info
 
 #define h_memalign memalign
@@ -37,7 +38,7 @@ extern "C" {
 #define h_mallinfo_arena_info mallinfo_arena_info
 #define h_mallinfo_bin_info mallinfo_bin_info
 
-#define h_iterate iterate
+#define h_malloc_iterate malloc_iterate
 #define h_malloc_disable malloc_disable
 #define h_malloc_enable malloc_enable
 
@@ -47,9 +48,10 @@ extern "C" {
 #endif
 
 // C standard
-void *h_malloc(size_t size);
-void *h_calloc(size_t nmemb, size_t size);
-void *h_realloc(void *ptr, size_t size);
+__attribute__((malloc)) __attribute__((alloc_size(1))) void *h_malloc(size_t size);
+__attribute__((malloc)) __attribute__((alloc_size(1, 2))) void *h_calloc(size_t nmemb, size_t size);
+__attribute__((alloc_size(2))) void *h_realloc(void *ptr, size_t size);
+__attribute__((malloc)) __attribute__((alloc_size(2))) __attribute__((alloc_align(1)))
 void *h_aligned_alloc(size_t alignment, size_t size);
 void h_free(void *ptr);
 
@@ -75,10 +77,11 @@ int h_malloc_info(int options, FILE *fp);
 #endif
 
 // obsolete glibc extensions
+__attribute__((malloc)) __attribute__((alloc_size(2))) __attribute__((alloc_align(1)))
 void *h_memalign(size_t alignment, size_t size);
 #ifndef __ANDROID__
-void *h_valloc(size_t size);
-void *h_pvalloc(size_t size);
+__attribute__((malloc)) __attribute__((alloc_size(1))) void *h_valloc(size_t size);
+__attribute__((malloc)) void *h_pvalloc(size_t size);
 #endif
 #ifdef __GLIBC__
 void h_cfree(void *ptr) __THROW;
@@ -92,19 +95,20 @@ size_t h_mallinfo_narenas(void);
 size_t h_mallinfo_nbins(void);
 struct mallinfo h_mallinfo_arena_info(size_t arena);
 struct mallinfo h_mallinfo_bin_info(size_t arena, size_t bin);
-int h_iterate(uintptr_t base, size_t size, void (*callback)(uintptr_t ptr, size_t size, void *arg),
+int h_malloc_iterate(uintptr_t base, size_t size, void (*callback)(uintptr_t ptr, size_t size, void *arg),
               void *arg);
 void h_malloc_disable(void);
 void h_malloc_enable(void);
+void h_malloc_disable_memory_tagging(void);
 #endif
 
 // hardened_malloc extensions
 
 // return an upper bound on object size for any pointer based on malloc metadata
-size_t h_malloc_object_size(void *ptr);
+size_t h_malloc_object_size(const void *ptr);
 
 // similar to malloc_object_size, but avoiding locking so the results are much more limited
-size_t h_malloc_object_size_fast(void *ptr);
+size_t h_malloc_object_size_fast(const void *ptr);
 
 // The free function with an extra parameter for passing the size requested at
 // allocation time.

memory.c

@@ -1,7 +1,10 @@
 #include <errno.h>
 
 #include <sys/mman.h>
+
+#ifdef LABEL_MEMORY
 #include <sys/prctl.h>
+#endif
 
 #ifndef PR_SET_VMA
 #define PR_SET_VMA 0x53564d41
@@ -14,8 +17,8 @@
 #include "memory.h"
 #include "util.h"
 
-void *memory_map(size_t size) {
-    void *p = mmap(NULL, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
+static void *memory_map_prot(size_t size, int prot) {
+    void *p = mmap(NULL, size, prot, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
     if (unlikely(p == MAP_FAILED)) {
         if (errno != ENOMEM) {
             fatal_error("non-ENOMEM mmap failure");
@@ -25,30 +28,50 @@ void *memory_map(size_t size) {
     return p;
 }
 
-int memory_map_fixed(void *ptr, size_t size) {
-    void *p = mmap(ptr, size, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0);
-    if (unlikely(p == MAP_FAILED)) {
-        if (errno != ENOMEM) {
-            fatal_error("non-ENOMEM MAP_FIXED mmap failure");
-        }
-        return 1;
-    }
-    return 0;
+void *memory_map(size_t size) {
+    return memory_map_prot(size, PROT_NONE);
 }
 
-int memory_unmap(void *ptr, size_t size) {
-    int ret = munmap(ptr, size);
+#ifdef HAS_ARM_MTE
+// Note that PROT_MTE can't be cleared via mprotect
+void *memory_map_mte(size_t size) {
+    return memory_map_prot(size, PROT_MTE);
+}
+#endif
+
+static bool memory_map_fixed_prot(void *ptr, size_t size, int prot) {
+    void *p = mmap(ptr, size, prot, MAP_ANONYMOUS|MAP_PRIVATE|MAP_FIXED, -1, 0);
+    bool ret = p == MAP_FAILED;
+    if (unlikely(ret) && errno != ENOMEM) {
+        fatal_error("non-ENOMEM MAP_FIXED mmap failure");
+    }
+    return ret;
+}
+
+bool memory_map_fixed(void *ptr, size_t size) {
+    return memory_map_fixed_prot(ptr, size, PROT_NONE);
+}
+
+#ifdef HAS_ARM_MTE
+// Note that PROT_MTE can't be cleared via mprotect
+bool memory_map_fixed_mte(void *ptr, size_t size) {
+    return memory_map_fixed_prot(ptr, size, PROT_MTE);
+}
+#endif
+
+bool memory_unmap(void *ptr, size_t size) {
+    bool ret = munmap(ptr, size);
     if (unlikely(ret) && errno != ENOMEM) {
         fatal_error("non-ENOMEM munmap failure");
     }
     return ret;
 }
 
-static int memory_protect_prot(void *ptr, size_t size, int prot, UNUSED int pkey) {
+static bool memory_protect_prot(void *ptr, size_t size, int prot, UNUSED int pkey) {
 #ifdef USE_PKEY
-    int ret = pkey_mprotect(ptr, size, prot, pkey);
+    bool ret = pkey_mprotect(ptr, size, prot, pkey);
 #else
-    int ret = mprotect(ptr, size, prot);
+    bool ret = mprotect(ptr, size, prot);
 #endif
     if (unlikely(ret) && errno != ENOMEM) {
         fatal_error("non-ENOMEM mprotect failure");
@@ -56,44 +79,50 @@ static int memory_protect_prot(void *ptr, size_t size, int prot, UNUSED int pkey
     return ret;
 }
 
-int memory_protect_ro(void *ptr, size_t size) {
+bool memory_protect_ro(void *ptr, size_t size) {
     return memory_protect_prot(ptr, size, PROT_READ, -1);
 }
 
-int memory_protect_rw(void *ptr, size_t size) {
+bool memory_protect_rw(void *ptr, size_t size) {
     return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE, -1);
 }
 
-int memory_protect_rw_metadata(void *ptr, size_t size) {
+bool memory_protect_rw_metadata(void *ptr, size_t size) {
     return memory_protect_prot(ptr, size, PROT_READ|PROT_WRITE, get_metadata_key());
 }
 
 #ifdef HAVE_COMPATIBLE_MREMAP
-int memory_remap(void *old, size_t old_size, size_t new_size) {
+bool memory_remap(void *old, size_t old_size, size_t new_size) {
     void *ptr = mremap(old, old_size, new_size, 0);
-    if (unlikely(ptr == MAP_FAILED)) {
-        if (errno != ENOMEM) {
+    bool ret = ptr == MAP_FAILED;
+    if (unlikely(ret) && errno != ENOMEM) {
         fatal_error("non-ENOMEM mremap failure");
     }
-        return 1;
-    }
-    return 0;
+    return ret;
 }
 
-int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size) {
+bool memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size) {
     void *ptr = mremap(old, old_size, new_size, MREMAP_MAYMOVE|MREMAP_FIXED, new);
-    if (unlikely(ptr == MAP_FAILED)) {
-        if (errno != ENOMEM) {
+    bool ret = ptr == MAP_FAILED;
+    if (unlikely(ret) && errno != ENOMEM) {
         fatal_error("non-ENOMEM MREMAP_FIXED mremap failure");
     }
-        return 1;
-    }
-    return 0;
+    return ret;
 }
 #endif
 
-void memory_set_name(UNUSED void *ptr, UNUSED size_t size, UNUSED const char *name) {
+bool memory_purge(void *ptr, size_t size) {
+    int ret = madvise(ptr, size, MADV_DONTNEED);
+    if (unlikely(ret) && errno != ENOMEM) {
+        fatal_error("non-ENOMEM MADV_DONTNEED madvise failure");
+    }
+    return ret;
+}
+
+bool memory_set_name(UNUSED void *ptr, UNUSED size_t size, UNUSED const char *name) {
 #ifdef LABEL_MEMORY
-    prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, name);
+    return prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, ptr, size, name);
+#else
+    return false;
 #endif
 }

memory.h

@@ -1,6 +1,7 @@
 #ifndef MEMORY_H
 #define MEMORY_H
 
+#include <stdbool.h>
 #include <stddef.h>
 
 #ifdef __linux__
@@ -10,15 +11,22 @@
 int get_metadata_key(void);
 
 void *memory_map(size_t size);
-int memory_map_fixed(void *ptr, size_t size);
-int memory_unmap(void *ptr, size_t size);
-int memory_protect_ro(void *ptr, size_t size);
-int memory_protect_rw(void *ptr, size_t size);
-int memory_protect_rw_metadata(void *ptr, size_t size);
-#ifdef HAVE_COMPATIBLE_MREMAP
-int memory_remap(void *old, size_t old_size, size_t new_size);
-int memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size);
+#ifdef HAS_ARM_MTE
+void *memory_map_mte(size_t size);
 #endif
-void memory_set_name(void *ptr, size_t size, const char *name);
+bool memory_map_fixed(void *ptr, size_t size);
+#ifdef HAS_ARM_MTE
+bool memory_map_fixed_mte(void *ptr, size_t size);
+#endif
+bool memory_unmap(void *ptr, size_t size);
+bool memory_protect_ro(void *ptr, size_t size);
+bool memory_protect_rw(void *ptr, size_t size);
+bool memory_protect_rw_metadata(void *ptr, size_t size);
+#ifdef HAVE_COMPATIBLE_MREMAP
+bool memory_remap(void *old, size_t old_size, size_t new_size);
+bool memory_remap_fixed(void *old, size_t old_size, void *new, size_t new_size);
+#endif
+bool memory_purge(void *ptr, size_t size);
+bool memory_set_name(void *ptr, size_t size, const char *name);
 
 #endif

memtag.h

@@ -0,0 +1,50 @@
+#ifndef MEMTAG_H
+#define MEMTAG_H
+
+#include "util.h"
+
+#ifdef HAS_ARM_MTE
+#include "arm_mte.h"
+#define MEMTAG 1
+// Note that bionic libc always reserves tag 0 via PR_MTE_TAG_MASK prctl
+#define RESERVED_TAG 0
+#define TAG_WIDTH 4
+#endif
+
+static inline void *untag_pointer(void *ptr) {
+#ifdef HAS_ARM_MTE
+    const uintptr_t mask = UINTPTR_MAX >> 8;
+    return (void *) ((uintptr_t) ptr & mask);
+#else
+    return ptr;
+#endif
+}
+
+static inline const void *untag_const_pointer(const void *ptr) {
+#ifdef HAS_ARM_MTE
+    const uintptr_t mask = UINTPTR_MAX >> 8;
+    return (const void *) ((uintptr_t) ptr & mask);
+#else
+    return ptr;
+#endif
+}
+
+static inline void *set_pointer_tag(void *ptr, u8 tag) {
+#ifdef HAS_ARM_MTE
+    return (void *) (((uintptr_t) tag << 56) | (uintptr_t) untag_pointer(ptr));
+#else
+    (void) tag;
+    return ptr;
+#endif
+}
+
+static inline u8 get_pointer_tag(void *ptr) {
+#ifdef HAS_ARM_MTE
+    return (((uintptr_t) ptr) >> 56) & 0xf;
+#else
+    (void) ptr;
+    return 0;
+#endif
+}
+
+#endif

new.cc

@@ -1,7 +1,9 @@
+// needed with libstdc++ but not libc++
+#if __has_include(<bits/functexcept.h>)
 #include <bits/functexcept.h>
-#include <new>
+#endif
 
-#define noreturn
+#include <new>
 
 #include "h_malloc.h"
 #include "util.h"
@@ -78,7 +80,6 @@ EXPORT void operator delete[](void *ptr, size_t size) noexcept {
     h_free_sized(ptr, size);
 }
 
-#if __cplusplus >= 201703L
 COLD static void *handle_out_of_memory(size_t size, size_t alignment, bool nothrow) {
     void *ptr = nullptr;
 
@@ -150,4 +151,3 @@ EXPORT void operator delete(void *ptr, size_t size, std::align_val_t) noexcept {
 EXPORT void operator delete[](void *ptr, size_t size, std::align_val_t) noexcept {
     h_free_sized(ptr, size);
 }
-#endif

pages.c

@@ -9,10 +9,6 @@ static bool add_guards(size_t size, size_t guard_size, size_t *total_size) {
         __builtin_add_overflow(*total_size, guard_size, total_size);
 }
 
-static uintptr_t alignment_ceiling(uintptr_t s, uintptr_t alignment) {
-    return ((s) + (alignment - 1)) & ((~alignment) + 1);
-}
-
 void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect, const char *name) {
     size_t real_size;
     if (unlikely(add_guards(usable_size, guard_size, &real_size))) {
@@ -33,7 +29,7 @@ void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect, cons
 }
 
 void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_size, const char *name) {
-    usable_size = PAGE_CEILING(usable_size);
+    usable_size = page_align(usable_size);
     if (unlikely(!usable_size)) {
         errno = ENOMEM;
         return NULL;
@@ -59,7 +55,7 @@ void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_
 
     void *usable = (char *)real + guard_size;
 
-    size_t lead_size = alignment_ceiling((uintptr_t)usable, alignment) - (uintptr_t)usable;
+    size_t lead_size = align((uintptr_t)usable, alignment) - (uintptr_t)usable;
     size_t trail_size = alloc_size - lead_size - usable_size;
     void *base = (char *)usable + lead_size;
 
@@ -86,5 +82,7 @@ void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_
 }
 
 void deallocate_pages(void *usable, size_t usable_size, size_t guard_size) {
-    memory_unmap((char *)usable - guard_size, usable_size + guard_size * 2);
+    if (unlikely(memory_unmap((char *)usable - guard_size, usable_size + guard_size * 2))) {
+        memory_purge(usable, usable_size);
+    }
 }

pages.h

@@ -5,16 +5,21 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "util.h"
+
 #define PAGE_SHIFT 12
 #ifndef PAGE_SIZE
 #define PAGE_SIZE ((size_t)1 << PAGE_SHIFT)
 #endif
-#define PAGE_CEILING(s) (((s) + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1))
 
 void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect, const char *name);
 void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t guard_size, const char *name);
 void deallocate_pages(void *usable, size_t usable_size, size_t guard_size);
 
+static inline size_t page_align(size_t size) {
+    return align(size, PAGE_SIZE);
+}
+
 static inline size_t hash_page(const void *p) {
     uintptr_t u = (uintptr_t)p >> PAGE_SHIFT;
     size_t sum = u;

test/.gitignore

@@ -1,4 +1,44 @@
 large_array_growth
 mallinfo
+mallinfo2
 malloc_info
 offset
+delete_type_size_mismatch
+double_free_large
+double_free_large_delayed
+double_free_small
+double_free_small_delayed
+invalid_free_protected
+invalid_free_small_region
+invalid_free_small_region_far
+invalid_free_unprotected
+read_after_free_large
+read_after_free_small
+read_zero_size
+string_overflow
+unaligned_free_large
+unaligned_free_small
+uninitialized_free
+uninitialized_malloc_usable_size
+uninitialized_realloc
+write_after_free_large
+write_after_free_large_reuse
+write_after_free_small
+write_after_free_small_reuse
+write_zero_size
+unaligned_malloc_usable_size_small
+invalid_malloc_usable_size_small
+invalid_malloc_usable_size_small_quarantine
+malloc_object_size
+malloc_object_size_offset
+invalid_malloc_object_size_small
+invalid_malloc_object_size_small_quarantine
+impossibly_large_malloc
+overflow_large_1_byte
+overflow_large_8_byte
+overflow_small_1_byte
+overflow_small_8_byte
+uninitialized_read_large
+uninitialized_read_small
+realloc_init
+__pycache__/

test/Makefile

@@ -1,24 +1,76 @@
 CONFIG_SLAB_CANARY := true
 CONFIG_EXTENDED_SIZE_CLASSES := true
 
+ifneq ($(VARIANT),)
+    $(error testing non-default variants not yet supported)
+endif
+
 ifeq (,$(filter $(CONFIG_SLAB_CANARY),true false))
     $(error CONFIG_SLAB_CANARY must be true or false)
 endif
 
-LDLIBS := -lpthread
+dir=$(dir $(realpath $(firstword $(MAKEFILE_LIST))))
 
-CPPFLAGS += \
+CPPFLAGS := \
+    -D_GNU_SOURCE \
     -DSLAB_CANARY=$(CONFIG_SLAB_CANARY) \
     -DCONFIG_EXTENDED_SIZE_CLASSES=$(CONFIG_EXTENDED_SIZE_CLASSES)
 
+SHARED_FLAGS := -O3
+
+CFLAGS := -std=c17 $(SHARED_FLAGS) -Wmissing-prototypes
+CXXFLAGS := -std=c++17 -fsized-deallocation $(SHARED_FLAGS)
+LDFLAGS := -Wl,-L$(dir)../out,-R,$(dir)../out
+
+LDLIBS := -lpthread -lhardened_malloc
+
 EXECUTABLES := \
     offset \
     mallinfo \
+    mallinfo2 \
     malloc_info \
-    large_array_growth
+    large_array_growth \
+    double_free_large \
+    double_free_large_delayed \
+    double_free_small \
+    double_free_small_delayed \
+    unaligned_free_large \
+    unaligned_free_small \
+    read_after_free_large \
+    read_after_free_small \
+    write_after_free_large \
+    write_after_free_large_reuse \
+    write_after_free_small \
+    write_after_free_small_reuse \
+    read_zero_size \
+    write_zero_size \
+    invalid_free_protected \
+    invalid_free_unprotected \
+    invalid_free_small_region \
+    invalid_free_small_region_far \
+    uninitialized_read_small \
+    uninitialized_read_large \
+    uninitialized_free \
+    uninitialized_realloc \
+    uninitialized_malloc_usable_size \
+    overflow_large_1_byte \
+    overflow_large_8_byte \
+    overflow_small_1_byte \
+    overflow_small_8_byte \
+    string_overflow \
+    delete_type_size_mismatch \
+    unaligned_malloc_usable_size_small \
+    invalid_malloc_usable_size_small \
+    invalid_malloc_usable_size_small_quarantine \
+    malloc_object_size \
+    malloc_object_size_offset \
+    invalid_malloc_object_size_small \
+    invalid_malloc_object_size_small_quarantine \
+    impossibly_large_malloc \
+    realloc_init
 
 all: $(EXECUTABLES)
-	make -C simple-memory-corruption
 
 clean:
 	rm -f $(EXECUTABLES)
+	rm -fr ./__pycache__

test/delete_type_size_mismatch.cc

@@ -1,11 +1,12 @@
 #include <stdint.h>
 
+#include "test_util.h"
+
 struct foo {
     uint64_t a, b, c, d;
 };
 
-__attribute__((optimize(0)))
-int main(void) {
+OPTNONE int main(void) {
     void *p = new char;
     struct foo *c = (struct foo *)p;
     delete c;

test/double_free_large.c

@@ -1,8 +1,9 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
-    void *p = malloc(128 * 1024);
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    void *p = malloc(256 * 1024);
     if (!p) {
         return 1;
     }

test/double_free_large_delayed.c

@@ -1,12 +1,13 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
-    void *p = malloc(128 * 1024);
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    void *p = malloc(256 * 1024);
     if (!p) {
         return 1;
     }
-    void *q = malloc(128 * 1024);
+    void *q = malloc(256 * 1024);
     if (!q) {
         return 1;
     }

test/double_free_small.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     void *p = malloc(16);
     if (!p) {
         return 1;

test/double_free_small_delayed.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     void *p = malloc(16);
     if (!p) {
         return 1;

test/impossibly_large_malloc.c

@@ -0,0 +1,8 @@
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(-8);
+    return !(p == NULL);
+}

test/invalid_free_protected.c

@@ -2,8 +2,9 @@
 
 #include <sys/mman.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     free(malloc(16));
     char *p = mmap(NULL, 4096 * 16, PROT_NONE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
     if (p == MAP_FAILED) {

test/invalid_free_small_region.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/invalid_free_small_region_far.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/invalid_free_unprotected.c

@@ -2,8 +2,9 @@
 
 #include <sys/mman.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     free(malloc(16));
     char *p = mmap(NULL, 4096 * 16, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0);
     if (p == MAP_FAILED) {

test/invalid_malloc_object_size_small.c

@@ -0,0 +1,15 @@
+#include <stdlib.h>
+
+#include "test_util.h"
+
+size_t malloc_object_size(void *ptr);
+
+OPTNONE int main(void) {
+    char *p = malloc(16);
+    if (!p) {
+        return 1;
+    }
+    char *q = p + 4096 * 4;
+    malloc_object_size(q);
+    return 0;
+}

test/invalid_malloc_object_size_small_quarantine.c

@@ -0,0 +1,15 @@
+#include <stdlib.h>
+
+#include "test_util.h"
+
+size_t malloc_object_size(void *ptr);
+
+OPTNONE int main(void) {
+    void *p = malloc(16);
+    if (!p) {
+        return 1;
+    }
+    free(p);
+    malloc_object_size(p);
+    return 0;
+}

test/invalid_malloc_usable_size_small.c

@@ -1,7 +1,8 @@
 #include <malloc.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/invalid_malloc_usable_size_small_quarantine.c

@@ -1,7 +1,8 @@
 #include <malloc.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     void *p = malloc(16);
     if (!p) {
         return 1;

test/large_array_growth.c

@@ -1,8 +1,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     void *p = NULL;
     size_t size = 256 * 1024;
 

test/mallinfo.c

@@ -1,21 +1,44 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+#if defined(__GLIBC__) || defined(__ANDROID__)
 #include <malloc.h>
+#endif
 
-__attribute__((optimize(0)))
-int main(void) {
-    malloc(1024 * 1024 * 1024);
-    malloc(16);
-    malloc(32);
-    malloc(64);
+#include "test_util.h"
 
+static void print_mallinfo(void) {
+#if defined(__GLIBC__) || defined(__ANDROID__)
     struct mallinfo info = mallinfo();
-    printf("arena: %zu\n", info.arena);
-    printf("ordblks: %zu\n", info.ordblks);
-    printf("smblks: %zu\n", info.smblks);
-    printf("hblks: %zu\n", info.hblks);
-    printf("hblkhd: %zu\n", info.hblkhd);
-    printf("usmblks: %zu\n", info.usmblks);
-    printf("fsmblks: %zu\n", info.fsmblks);
-    printf("uordblks: %zu\n", info.uordblks);
-    printf("fordblks: %zu\n", info.fordblks);
-    printf("keepcost: %zu\n", info.keepcost);
+    printf("mallinfo:\n");
+    printf("arena: %zu\n", (size_t)info.arena);
+    printf("ordblks: %zu\n", (size_t)info.ordblks);
+    printf("smblks: %zu\n", (size_t)info.smblks);
+    printf("hblks: %zu\n", (size_t)info.hblks);
+    printf("hblkhd: %zu\n", (size_t)info.hblkhd);
+    printf("usmblks: %zu\n", (size_t)info.usmblks);
+    printf("fsmblks: %zu\n", (size_t)info.fsmblks);
+    printf("uordblks: %zu\n", (size_t)info.uordblks);
+    printf("fordblks: %zu\n", (size_t)info.fordblks);
+    printf("keepcost: %zu\n", (size_t)info.keepcost);
+#endif
+}
+
+OPTNONE int main(void) {
+    void *a[4];
+
+    a[0] = malloc(1024 * 1024 * 1024);
+    a[1] = malloc(16);
+    a[2] = malloc(32);
+    a[3] = malloc(64);
+
+    print_mallinfo();
+
+    free(a[0]);
+    free(a[1]);
+    free(a[2]);
+    free(a[3]);
+
+    printf("\n");
+    print_mallinfo();
 }

test/mallinfo2.c

@@ -0,0 +1,44 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+#if defined(__GLIBC__)
+#include <malloc.h>
+#endif
+
+#include "test_util.h"
+
+static void print_mallinfo2(void) {
+#if defined(__GLIBC__)
+    struct mallinfo2 info = mallinfo2();
+    printf("mallinfo2:\n");
+    printf("arena: %zu\n", (size_t)info.arena);
+    printf("ordblks: %zu\n", (size_t)info.ordblks);
+    printf("smblks: %zu\n", (size_t)info.smblks);
+    printf("hblks: %zu\n", (size_t)info.hblks);
+    printf("hblkhd: %zu\n", (size_t)info.hblkhd);
+    printf("usmblks: %zu\n", (size_t)info.usmblks);
+    printf("fsmblks: %zu\n", (size_t)info.fsmblks);
+    printf("uordblks: %zu\n", (size_t)info.uordblks);
+    printf("fordblks: %zu\n", (size_t)info.fordblks);
+    printf("keepcost: %zu\n", (size_t)info.keepcost);
+#endif
+}
+
+OPTNONE int main(void) {
+    void *a[4];
+
+    a[0] = malloc(1024 * 1024 * 1024);
+    a[1] = malloc(16);
+    a[2] = malloc(32);
+    a[3] = malloc(64);
+
+    print_mallinfo2();
+
+    free(a[0]);
+    free(a[1]);
+    free(a[2]);
+    free(a[3]);
+
+    printf("\n");
+    print_mallinfo2();
+}

test/malloc_info.c

@@ -1,16 +1,22 @@
 #include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
 
+#if defined(__GLIBC__) || defined(__ANDROID__)
 #include <malloc.h>
+#endif
 
-__attribute__((optimize(0)))
-void leak_memory(void) {
-    (void)malloc(1024 * 1024 * 1024);
-    (void)malloc(16);
-    (void)malloc(32);
-    (void)malloc(4096);
+#include "test_util.h"
+#include "../util.h"
+
+OPTNONE static void leak_memory(void) {
+    (void)!malloc(1024 * 1024 * 1024);
+    (void)!malloc(16);
+    (void)!malloc(32);
+    (void)!malloc(4096);
 }
 
-void *do_work(void *p) {
+static void *do_work(UNUSED void *p) {
     leak_memory();
     return NULL;
 }
@@ -24,5 +30,7 @@ int main(void) {
         pthread_join(thread[i], NULL);
     }
 
+#if defined(__GLIBC__) || defined(__ANDROID__)
     malloc_info(0, stdout);
+#endif
 }

test/malloc_object_size.c

@@ -0,0 +1,12 @@
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+size_t malloc_object_size(void *ptr);
+
+OPTNONE int main(void) {
+    char *p = malloc(16);
+    size_t size = malloc_object_size(p);
+    return size != (SLAB_CANARY ? 24 : 32);
+}

test/malloc_object_size_offset.c

@@ -0,0 +1,12 @@
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+size_t malloc_object_size(void *ptr);
+
+OPTNONE int main(void) {
+    char *p = malloc(16);
+    size_t size = malloc_object_size(p + 5);
+    return size != (SLAB_CANARY ? 19 : 27);
+}

test/offset.c

@@ -3,7 +3,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-static unsigned size_classes[] = {
+static size_t size_classes[] = {
     /* large */ 4 * 1024 * 1024,
     /* 0 */ 0,
     /* 16 */ 16, 32, 48, 64, 80, 96, 112, 128,
@@ -32,9 +32,9 @@ int main(void) {
 
     void *p[N_SIZE_CLASSES];
     for (unsigned i = 0; i < N_SIZE_CLASSES; i++) {
-        unsigned size = size_classes[i];
+        size_t size = size_classes[i];
         p[i] = malloc(size);
-        if (!p) {
+        if (!p[i]) {
             return 1;
         }
         void *q = malloc(size);

test/overflow_large_1_byte.c

@@ -0,0 +1,15 @@
+#include <malloc.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
+    if (!p) {
+        return 1;
+    }
+    size_t size = malloc_usable_size(p);
+    *(p + size) = 0;
+    free(p);
+    return 0;
+}

test/overflow_large_8_byte.c

@@ -0,0 +1,15 @@
+#include <malloc.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
+    if (!p) {
+        return 1;
+    }
+    size_t size = malloc_usable_size(p);
+    *(p + size + 7) = 0;
+    free(p);
+    return 0;
+}

test/overflow_small_1_byte.c

@@ -0,0 +1,15 @@
+#include <malloc.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(8);
+    if (!p) {
+        return 1;
+    }
+    size_t size = malloc_usable_size(p);
+    *(p + size) = 1;
+    free(p);
+    return 0;
+}

test/overflow_small_8_byte.c

@@ -0,0 +1,16 @@
+#include <malloc.h>
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(8);
+    if (!p) {
+        return 1;
+    }
+    size_t size = malloc_usable_size(p);
+    // XOR is used to avoid the test having a 1/256 chance to fail
+    *(p + size + 7) ^= 1;
+    free(p);
+    return 0;
+}

test/read_after_free_large.c

@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
+    if (!p) {
+        return 1;
+    }
+    memset(p, 'a', 16);
+    free(p);
+    for (size_t i = 0; i < 256 * 1024; i++) {
+        printf("%x\n", p[i]);
+        if (p[i] != '\0') {
+            return 1;
+        }
+    }
+    return 0;
+}

test/read_after_free_small.c

@@ -2,8 +2,9 @@
 #include <stdlib.h>
 #include <string.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;
@@ -12,6 +13,9 @@ int main(void) {
     free(p);
     for (size_t i = 0; i < 16; i++) {
         printf("%x\n", p[i]);
+        if (p[i] != '\0') {
+            return 1;
+        }
     }
     return 0;
 }

test/read_zero_size.c

@@ -1,8 +1,9 @@
 #include <stdlib.h>
 #include <stdio.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(0);
     if (!p) {
         return 1;

test/realloc_init.c

@@ -0,0 +1,33 @@
+#include <pthread.h>
+#include <stdlib.h>
+
+static void *thread_func(void *arg) {
+    arg = realloc(arg, 1024);
+    if (!arg) {
+        exit(EXIT_FAILURE);
+    }
+
+    free(arg);
+
+    return NULL;
+}
+
+int main(void) {
+    void *mem = realloc(NULL, 12);
+    if (!mem) {
+        return EXIT_FAILURE;
+    }
+
+    pthread_t thread;
+    int r = pthread_create(&thread, NULL, thread_func, mem);
+    if (r != 0) {
+        return EXIT_FAILURE;
+    }
+
+    r = pthread_join(thread, NULL);
+    if (r != 0) {
+        return EXIT_FAILURE;
+    }
+
+    return EXIT_SUCCESS;
+}

test/simple-memory-corruption/.gitignore

@@ -1,29 +0,0 @@
-delete_type_size_mismatch
-double_free_large
-double_free_large_delayed
-double_free_small
-double_free_small_delayed
-eight_byte_overflow_large
-eight_byte_overflow_small
-invalid_free_protected
-invalid_free_small_region
-invalid_free_small_region_far
-invalid_free_unprotected
-read_after_free_large
-read_after_free_small
-read_zero_size
-string_overflow
-unaligned_free_large
-unaligned_free_small
-uninitialized_free
-uninitialized_malloc_usable_size
-uninitialized_realloc
-write_after_free_large
-write_after_free_large_reuse
-write_after_free_small
-write_after_free_small_reuse
-write_zero_size
-unaligned_malloc_usable_size_small
-invalid_malloc_usable_size_small
-invalid_malloc_usable_size_small_quarantine
-__pycache__/

test/simple-memory-corruption/Makefile

@@ -1,34 +0,0 @@
-EXECUTABLES := \
-    double_free_large \
-    double_free_large_delayed \
-    double_free_small \
-    double_free_small_delayed \
-    unaligned_free_large \
-    unaligned_free_small \
-    read_after_free_large \
-    read_after_free_small \
-    write_after_free_large \
-    write_after_free_large_reuse \
-    write_after_free_small \
-    write_after_free_small_reuse \
-    read_zero_size \
-    write_zero_size \
-    invalid_free_protected \
-    invalid_free_unprotected \
-    invalid_free_small_region \
-    invalid_free_small_region_far \
-    uninitialized_free \
-    uninitialized_realloc \
-    uninitialized_malloc_usable_size \
-    eight_byte_overflow_small \
-    eight_byte_overflow_large \
-    string_overflow \
-    delete_type_size_mismatch \
-	unaligned_malloc_usable_size_small \
-	invalid_malloc_usable_size_small \
-	invalid_malloc_usable_size_small_quarantine
-
-all: $(EXECUTABLES)
-
-clean:
-	rm -f $(EXECUTABLES)

test/simple-memory-corruption/eight_byte_overflow_small.c

@@ -1,12 +0,0 @@
-#include <stdlib.h>
-
-__attribute__((optimize(0)))
-int main(void) {
-    char *p = malloc(8);
-    if (!p) {
-        return 1;
-    }
-    *(p + 8 + 7) = 0;
-    free(p);
-    return 0;
-}

test/simple-memory-corruption/read_after_free_large.c

@@ -1,17 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-
-__attribute__((optimize(0)))
-int main(void) {
-    char *p = malloc(128 * 1024);
-    if (!p) {
-        return 1;
-    }
-    memset(p, 'a', 16);
-    free(p);
-    for (size_t i = 0; i < 128 * 1024; i++) {
-        printf("%x\n", p[i]);
-    }
-    return 0;
-}

test/simple-memory-corruption/write_after_free_large.c

@@ -1,13 +0,0 @@
-#include <stdlib.h>
-#include <string.h>
-
-__attribute__((optimize(0)))
-int main(void) {
-    char *p = malloc(128 * 1024);
-    if (!p) {
-        return 1;
-    }
-    free(p);
-    p[64 * 1024 + 1] = 'a';
-    return 0;
-}

test/simple-memory-corruption/write_after_free_large_reuse.c

@@ -1,14 +0,0 @@
-#include <stdlib.h>
-#include <string.h>
-
-__attribute__((optimize(0)))
-int main(void) {
-    char *p = malloc(128 * 1024);
-    if (!p) {
-        return 1;
-    }
-    free(p);
-    char *q = malloc(128 * 1024);
-    p[64 * 1024 + 1] = 'a';
-    return 0;
-}

test/string_overflow.c

@@ -4,8 +4,9 @@
 
 #include <malloc.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/test_smc.py

@@ -48,14 +48,26 @@ class TestSimpleMemoryCorruption(unittest.TestCase):
         self.assertEqual(stderr.decode("utf-8"),
                          "fatal allocator error: double free (quarantine)\n")
 
-    def test_eight_byte_overflow_large(self):
+    def test_overflow_large_1_byte(self):
         _stdout, _stderr, returncode = self.run_test(
-            "eight_byte_overflow_large")
+            "overflow_large_1_byte")
         self.assertEqual(returncode, -11)
 
-    def test_eight_byte_overflow_small(self):
+    def test_overflow_large_8_byte(self):
+        _stdout, _stderr, returncode = self.run_test(
+            "overflow_large_8_byte")
+        self.assertEqual(returncode, -11)
+
+    def test_overflow_small_1_byte(self):
         _stdout, stderr, returncode = self.run_test(
-            "eight_byte_overflow_small")
+            "overflow_small_1_byte")
+        self.assertEqual(returncode, -6)
+        self.assertEqual(stderr.decode("utf-8"),
+                         "fatal allocator error: canary corrupted\n")
+
+    def test_overflow_small_8_byte(self):
+        _stdout, stderr, returncode = self.run_test(
+            "overflow_small_8_byte")
         self.assertEqual(returncode, -6)
         self.assertEqual(stderr.decode("utf-8"),
                          "fatal allocator error: canary corrupted\n")
@@ -145,9 +157,11 @@ class TestSimpleMemoryCorruption(unittest.TestCase):
                          "fatal allocator error: invalid free\n")
 
     def test_uninitialized_malloc_usable_size(self):
-        _stdout, _stderr, returncode = self.run_test(
+        _stdout, stderr, returncode = self.run_test(
             "uninitialized_malloc_usable_size")
-        self.assertEqual(returncode, -11)
+        self.assertEqual(returncode, -6)
+        self.assertEqual(stderr.decode("utf-8"),
+                         "fatal allocator error: invalid malloc_usable_size\n")
 
     def test_uninitialized_realloc(self):
         _stdout, stderr, returncode = self.run_test("uninitialized_realloc")
@@ -181,6 +195,48 @@ class TestSimpleMemoryCorruption(unittest.TestCase):
         _stdout, _stderr, returncode = self.run_test("write_zero_size")
         self.assertEqual(returncode, -11)
 
+    def test_malloc_object_size(self):
+        _stdout, _stderr, returncode = self.run_test("malloc_object_size")
+        self.assertEqual(returncode, 0)
+
+    def test_malloc_object_size_offset(self):
+        _stdout, _stderr, returncode = self.run_test(
+            "malloc_object_size_offset")
+        self.assertEqual(returncode, 0)
+
+    def test_invalid_malloc_object_size_small(self):
+        _stdout, stderr, returncode = self.run_test(
+            "invalid_malloc_object_size_small")
+        self.assertEqual(returncode, -6)
+        self.assertEqual(stderr.decode(
+            "utf-8"), "fatal allocator error: invalid malloc_object_size\n")
+
+    def test_invalid_malloc_object_size_small_quarantine(self):
+        _stdout, stderr, returncode = self.run_test(
+            "invalid_malloc_object_size_small_quarantine")
+        self.assertEqual(returncode, -6)
+        self.assertEqual(stderr.decode(
+            "utf-8"), "fatal allocator error: invalid malloc_object_size (quarantine)\n")
+
+    def test_impossibly_large_malloc(self):
+        _stdout, stderr, returncode = self.run_test(
+            "impossibly_large_malloc")
+        self.assertEqual(returncode, 0)
+
+    def test_uninitialized_read_small(self):
+        _stdout, stderr, returncode = self.run_test(
+            "uninitialized_read_small")
+        self.assertEqual(returncode, 0)
+
+    def test_uninitialized_read_large(self):
+        _stdout, stderr, returncode = self.run_test(
+            "uninitialized_read_large")
+        self.assertEqual(returncode, 0)
+
+    def test_realloc_init(self):
+        _stdout, _stderr, returncode = self.run_test(
+            "realloc_init")
+        self.assertEqual(returncode, 0)
 
 if __name__ == '__main__':
     unittest.main()

test/test_util.h

@@ -0,0 +1,10 @@
+#ifndef TEST_UTIL_H
+#define TEST_UTIL_H
+
+#ifdef __clang__
+#define OPTNONE __attribute__((optnone))
+#else
+#define OPTNONE __attribute__((optimize(0)))
+#endif
+
+#endif

test/unaligned_free_large.c

@@ -1,8 +1,9 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
-    char *p = malloc(128 * 1024);
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
     if (!p) {
         return 1;
     }

test/unaligned_free_small.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/unaligned_malloc_usable_size_small.c

@@ -1,7 +1,8 @@
 #include <malloc.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(16);
     if (!p) {
         return 1;

test/uninitialized_free.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     free((void *)1);
     return 0;
 }

test/uninitialized_malloc_usable_size.c

@@ -1,7 +1,8 @@
 #include <malloc.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     malloc_usable_size((void *)1);
     return 0;
 }

test/uninitialized_read_large.c

@@ -0,0 +1,14 @@
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
+    for (unsigned i = 0; i < 256 * 1024; i++) {
+        if (p[i] != 0) {
+            return 1;
+        }
+    }
+    free(p);
+    return 0;
+}

test/uninitialized_read_small.c

@@ -0,0 +1,14 @@
+#include <stdlib.h>
+
+#include "test_util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(8);
+    for (unsigned i = 0; i < 8; i++) {
+        if (p[i] != 0) {
+            return 1;
+        }
+    }
+    free(p);
+    return 0;
+}

test/uninitialized_realloc.c

@@ -1,7 +1,8 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     void *p = realloc((void *)1, 16);
     if (!p) {
         return 1;

test/write_after_free_large.c

@@ -1,12 +1,13 @@
 #include <stdlib.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(256 * 1024);
     if (!p) {
         return 1;
     }
-    *(p + 256 * 1024 + 7) = 0;
     free(p);
+    p[64 * 1024 + 1] = 'a';
     return 0;
 }

test/write_after_free_large_reuse.c

@@ -0,0 +1,16 @@
+#include <stdlib.h>
+#include <string.h>
+
+#include "test_util.h"
+#include "../util.h"
+
+OPTNONE int main(void) {
+    char *p = malloc(256 * 1024);
+    if (!p) {
+        return 1;
+    }
+    free(p);
+    UNUSED char *q = malloc(256 * 1024);
+    p[64 * 1024 + 1] = 'a';
+    return 0;
+}

test/write_after_free_small.c

@@ -1,8 +1,8 @@
 #include <stdlib.h>
-#include <string.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(128);
     if (!p) {
         return 1;

test/write_after_free_small_reuse.c

@@ -1,14 +1,15 @@
 #include <stdlib.h>
-#include <string.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+#include "../util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(128);
     if (!p) {
         return 1;
     }
     free(p);
-    char *q = malloc(128);
+    UNUSED char *q = malloc(128);
 
     p[65] = 'a';
 

test/write_zero_size.c

@@ -1,8 +1,8 @@
 #include <stdlib.h>
-#include <stdio.h>
 
-__attribute__((optimize(0)))
-int main(void) {
+#include "test_util.h"
+
+OPTNONE int main(void) {
     char *p = malloc(0);
     if (!p) {
         return 1;

util.c

@@ -4,8 +4,15 @@
 
 #include <unistd.h>
 
+#ifdef __ANDROID__
+#include <async_safe/log.h>
+int mallopt(int param, int value);
+#define M_BIONIC_RESTORE_DEFAULT_SIGABRT_HANDLER (-1003)
+#endif
+
 #include "util.h"
 
+#ifndef __ANDROID__
 static int write_full(int fd, const char *buf, size_t length) {
     do {
         ssize_t bytes_written = write(fd, buf, length);
@@ -21,11 +28,17 @@ static int write_full(int fd, const char *buf, size_t length) {
 
     return 0;
 }
+#endif
 
 COLD noreturn void fatal_error(const char *s) {
+#ifdef __ANDROID__
+    mallopt(M_BIONIC_RESTORE_DEFAULT_SIGABRT_HANDLER, 0);
+    async_safe_fatal("hardened_malloc: fatal allocator error: %s", s);
+#else
     const char *prefix = "fatal allocator error: ";
     (void)(write_full(STDERR_FILENO, prefix, strlen(prefix)) != -1 &&
         write_full(STDERR_FILENO, s, strlen(s)) != -1 &&
         write_full(STDERR_FILENO, "\n", 1));
     abort();
+#endif
 }

util.h

@@ -1,11 +1,17 @@
 #ifndef UTIL_H
 #define UTIL_H
 
+#include <stdbool.h>
+#include <stddef.h>
 #include <stdint.h>
-#include <stdnoreturn.h>
+
+// C11 noreturn doesn't work in C++
+#define noreturn __attribute__((noreturn))
 
 #define likely(x) __builtin_expect(!!(x), 1)
+#define likely51(x) __builtin_expect_with_probability(!!(x), 1, 0.51)
 #define unlikely(x) __builtin_expect(!!(x), 0)
+#define unlikely51(x) __builtin_expect_with_probability(!!(x), 0, 0.51)
 
 #define min(x, y) ({ \
     __typeof__(x) _x = (x); \
@@ -26,11 +32,12 @@
 #define STRINGIFY(s) #s
 #define ALIAS(f) __attribute__((alias(STRINGIFY(f))))
 
-static inline int ffzl(long x) {
-    return __builtin_ffsl(~x);
-}
-
-COLD noreturn void fatal_error(const char *s);
+// supported since GCC 15
+#if __has_attribute (nonstring)
+#  define NONSTRING __attribute__ ((nonstring))
+#else
+#  define NONSTRING
+#endif
 
 typedef uint8_t u8;
 typedef uint16_t u16;
@@ -38,6 +45,45 @@ typedef uint32_t u32;
 typedef uint64_t u64;
 typedef unsigned __int128 u128;
 
+#define U64_WIDTH 64
+
+static inline int ffz64(u64 x) {
+    return __builtin_ffsll(~x);
+}
+
+// parameter must not be 0
+static inline int clz64(u64 x) {
+    return __builtin_clzll(x);
+}
+
+// parameter must not be 0
+static inline u64 log2u64(u64 x) {
+    return U64_WIDTH - clz64(x) - 1;
+}
+
+static inline size_t align(size_t size, size_t align) {
+    size_t mask = align - 1;
+    return (size + mask) & ~mask;
+}
+
+// u4_arr_{set,get} are helper functions for using u8 array as an array of unsigned 4-bit values.
+
+// val is treated as a 4-bit value
+static inline void u4_arr_set(u8 *arr, size_t idx, u8 val) {
+    size_t off = idx >> 1;
+    size_t shift = (idx & 1) << 2;
+    u8 mask = (u8) (0xf0 >> shift);
+    arr[off] = (arr[off] & mask) | (val << shift);
+}
+
+static inline u8 u4_arr_get(const u8 *arr, size_t idx) {
+    size_t off = idx >> 1;
+    size_t shift = (idx & 1) << 2;
+    return (u8) ((arr[off] >> shift) & 0xf);
+}
+
+COLD noreturn void fatal_error(const char *s);
+
 #if CONFIG_SEAL_METADATA
 
 #ifdef __GLIBC__