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2025012702
9 changed files with 33 additions and 43 deletions
14
.github/workflows/build-and-test.yml
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14
.github/workflows/build-and-test.yml
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@ -11,9 +11,9 @@ jobs:
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runs-on: ubuntu-latest
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strategy:
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matrix:
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version: [14]
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version: [12, 13, 14]
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steps:
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- uses: actions/checkout@v6
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- uses: actions/checkout@v4
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- name: Setting up gcc version
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run: |
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sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-${{ matrix.version }} 100
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@ -24,11 +24,11 @@ jobs:
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runs-on: ubuntu-latest
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strategy:
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matrix:
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version: [19, 20]
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version: [14, 15, 16, 17, 18]
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steps:
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- uses: actions/checkout@v6
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- uses: actions/checkout@v4
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- name: Install dependencies
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run: sudo apt-get update && sudo apt-get install -y --no-install-recommends clang-19 clang-20
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run: sudo apt-get update && sudo apt-get install -y --no-install-recommends clang-14 clang-15
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- name: Setting up clang version
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run: |
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sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-${{ matrix.version }} 100
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@ -40,7 +40,7 @@ jobs:
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container:
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image: alpine:latest
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steps:
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- uses: actions/checkout@v6
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- uses: actions/checkout@v4
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- name: Install dependencies
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run: apk update && apk add build-base python3
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- name: Build
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@ -48,7 +48,7 @@ jobs:
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build-ubuntu-gcc-aarch64:
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runs-on: ubuntu-latest
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steps:
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- uses: actions/checkout@v6
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- uses: actions/checkout@v4
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- name: Install dependencies
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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
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- name: Build
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4
.gitignore
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4
.gitignore
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@ -1,2 +1,2 @@
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/out/
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/out-light/
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out/
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out-light/
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2
LICENSE
2
LICENSE
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@ -1,4 +1,4 @@
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Copyright © 2018-2025 GrapheneOS
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Copyright © 2018-2024 GrapheneOS
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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43
README.md
43
README.md
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@ -1,4 +1,4 @@
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# hardened_malloc
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# Hardened malloc
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* [Introduction](#introduction)
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* [Dependencies](#dependencies)
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@ -65,14 +65,14 @@ used instead as this allocator fundamentally doesn't support that environment.
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## Dependencies
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Debian stable (currently Debian 13) determines the most ancient set of
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Debian stable (currently Debian 12) determines the most ancient set of
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supported dependencies:
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* glibc 2.41
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* Linux 6.12
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* Clang 19.1.7 or GCC 14.2.0
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* glibc 2.36
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* Linux 6.1
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* Clang 14.0.6 or GCC 12.2.0
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For Android, the Linux GKI 6.1, 6.6 and 6.12 branches are supported.
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For Android, the Linux GKI 5.10, 5.15 and 6.1 branches are supported.
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However, using more recent releases is highly recommended. Older versions of
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the dependencies may be compatible at the moment but are not tested and will
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@ -83,7 +83,7 @@ there will be custom integration offering better performance in the future
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along with other hardening for the C standard library implementation.
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For Android, only the current generation, actively developed maintenance branch of the Android
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Open Source Project will be supported, which currently means `android16-qpr1-release`.
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Open Source Project will be supported, which currently means `android15-release`.
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## Testing
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@ -159,17 +159,14 @@ line to the `/etc/ld.so.preload` configuration file:
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The format of this configuration file is a whitespace-separated list, so it's
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good practice to put each library on a separate line.
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For maximum compatibility `libhardened_malloc.so` can be installed into
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`/usr/lib/` to avoid preload failures caused by AppArmor profiles or systemd
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ExecPaths= restrictions. Check for logs of the following format:
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ERROR: ld.so: object '/usr/local/lib/libhardened_malloc.so' from /etc/ld.so.preload cannot be preloaded (failed to map segment from shared object): ignored.
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On Debian systems `libhardened_malloc.so` should be installed into `/usr/lib/`
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to avoid preload failures caused by AppArmor profile restrictions.
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Using the `LD_PRELOAD` environment variable to load it on a case-by-case basis
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will not work when `AT_SECURE` is set such as with setuid binaries. It's also
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generally not a recommended approach for production usage. The recommendation
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is to enable it globally and make exceptions for performance critical cases by
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running the application in a container/namespace without it enabled.
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running the application in a container / namespace without it enabled.
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Make sure to raise `vm.max_map_count` substantially too to accommodate the very
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large number of guard pages created by hardened\_malloc. As an example, in
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@ -255,7 +252,7 @@ The following boolean configuration options are available:
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* `CONFIG_WRITE_AFTER_FREE_CHECK`: `true` (default) or `false` to control
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sanity checking that new small allocations contain zeroed memory. This can
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detect writes caused by a write-after-free vulnerability and mixes well with
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the features for making memory reuse randomized/delayed. This has a
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the features for making memory reuse randomized / delayed. This has a
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performance cost scaling to the size of the allocation, which is usually
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acceptable. This is not relevant to large allocations because they're always
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a fresh memory mapping from the kernel.
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@ -341,7 +338,7 @@ larger caches can substantially improves performance).
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## Core design
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The core design of the allocator is very simple/minimalist. The allocator is
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The core design of the allocator is very simple / minimalist. The allocator is
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exclusive to 64-bit platforms in order to take full advantage of the abundant
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address space without being constrained by needing to keep the design
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compatible with 32-bit.
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@ -373,13 +370,13 @@ whether it's free, along with a separate bitmap for tracking allocations in the
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quarantine. The slab metadata entries in the array have intrusive lists
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threaded through them to track partial slabs (partially filled, and these are
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the first choice for allocation), empty slabs (limited amount of cached free
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memory) and free slabs (purged/memory protected).
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memory) and free slabs (purged / memory protected).
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Large allocations are tracked via a global hash table mapping their address to
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their size and random guard size. They're simply memory mappings and get mapped
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on allocation and then unmapped on free. Large allocations are the only dynamic
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memory mappings made by the allocator, since the address space for allocator
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state (including both small/large allocation metadata) and slab allocations
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state (including both small / large allocation metadata) and slab allocations
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is statically reserved.
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This allocator is aimed at production usage, not aiding with finding and fixing
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@ -390,7 +387,7 @@ messages. The design choices are based around minimizing overhead and
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maximizing security which often leads to different decisions than a tool
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attempting to find bugs. For example, it uses zero-based sanitization on free
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and doesn't minimize slack space from size class rounding between the end of an
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allocation and the canary/guard region. Zero-based filling has the least
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allocation and the canary / guard region. Zero-based filling has the least
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chance of uncovering latent bugs, but also the best chance of mitigating
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vulnerabilities. The canary feature is primarily meant to act as padding
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absorbing small overflows to render them harmless, so slack space is helpful
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@ -424,11 +421,11 @@ was a bit less important and if a core goal was finding latent bugs.
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* Top-level isolated regions for each arena
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* Divided up into isolated inner regions for each size class
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* High entropy random base for each size class region
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* No deterministic/low entropy offsets between allocations with
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* No deterministic / low entropy offsets between allocations with
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different size classes
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* Metadata is completely outside the slab allocation region
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* No references to metadata within the slab allocation region
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* No deterministic/low entropy offsets to metadata
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* No deterministic / low entropy offsets to metadata
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* Entire slab region starts out non-readable and non-writable
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* Slabs beyond the cache limit are purged and become non-readable and
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non-writable memory again
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@ -649,7 +646,7 @@ other. Static assignment can also reduce memory usage since threads may have
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varying usage of size classes.
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When there's substantial allocation or deallocation pressure, the allocator
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does end up calling into the kernel to purge/protect unused slabs by
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does end up calling into the kernel to purge / protect unused slabs by
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replacing them with fresh `PROT_NONE` regions along with unprotecting slabs
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when partially filled and cached empty slabs are depleted. There will be
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configuration over the amount of cached empty slabs, but it's not entirely a
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@ -696,7 +693,7 @@ The secondary benefit of thread caches is being able to avoid the underlying
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allocator implementation entirely for some allocations and deallocations when
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they're mixed together rather than many allocations being done together or many
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frees being done together. The value of this depends a lot on the application
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and it's entirely unsuitable/incompatible with a hardened allocator since it
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and it's entirely unsuitable / incompatible with a hardened allocator since it
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bypasses all of the underlying security and would destroy much of the security
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value.
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@ -960,7 +957,7 @@ doesn't handle large allocations within the arenas, so it presents those in the
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For example, with 4 arenas enabled, there will be a 5th arena in the statistics
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for the large allocations.
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The `nmalloc`/`ndalloc` fields are 64-bit integers tracking allocation and
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The `nmalloc` / `ndalloc` fields are 64-bit integers tracking allocation and
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deallocation count. These are defined as wrapping on overflow, per the jemalloc
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implementation.
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@ -44,7 +44,7 @@ void *set_pointer_tag(void *ptr, u8 tag) {
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return (void *) (((uintptr_t) tag << 56) | (uintptr_t) untag_pointer(ptr));
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}
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// This test checks that slab slot allocation uses tag that is distinct from tags of its neighbors
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// This test checks that slab slot allocation uses tag that is distint from tags of its neighbors
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// and from the tag of the previous allocation that used the same slot
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void tag_distinctness() {
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// tag 0 is reserved
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2
chacha.c
2
chacha.c
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@ -41,7 +41,7 @@ static const unsigned rounds = 8;
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a = PLUS(a, b); d = ROTATE(XOR(d, a), 8); \
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c = PLUS(c, d); b = ROTATE(XOR(b, c), 7);
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static const char sigma[16] NONSTRING = "expand 32-byte k";
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static const char sigma[16] = "expand 32-byte k";
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void chacha_keysetup(chacha_ctx *x, const u8 *k) {
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x->input[0] = U8TO32_LITTLE(sigma + 0);
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@ -98,7 +98,7 @@ class TestSimpleMemoryCorruption(unittest.TestCase):
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self.assertEqual(stderr.decode("utf-8"),
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"fatal allocator error: invalid free\n")
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def test_invalid_malloc_usable_size_small_quarantine(self):
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def test_invalid_malloc_usable_size_small_quarantene(self):
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_stdout, stderr, returncode = self.run_test(
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"invalid_malloc_usable_size_small_quarantine")
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self.assertEqual(returncode, -6)
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7
util.h
7
util.h
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@ -32,13 +32,6 @@
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#define STRINGIFY(s) #s
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#define ALIAS(f) __attribute__((alias(STRINGIFY(f))))
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// supported since GCC 15
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#if __has_attribute (nonstring)
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# define NONSTRING __attribute__ ((nonstring))
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#else
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# define NONSTRING
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#endif
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typedef uint8_t u8;
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typedef uint16_t u16;
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typedef uint32_t u32;
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