add configuration for self-init

This needs to be disabled for compatibility with the exploit protection
compatibility mode on GrapheneOS. hardened_malloc shouldn't be trying to
initialize itself when exploit protection compatibility mode is enabled.
This has to be handled in our Bionic integration instead.

Android.bp

@@ -29,6 +29,7 @@ common_cflags = [
     "-DCONFIG_CLASS_REGION_SIZE=34359738368", // 32GiB
     "-DN_ARENA=1",
     "-DCONFIG_STATS=true",
+    "-DCONFIG_SELF_INIT=false",
 ]
 
 cc_defaults {

Makefile

@@ -84,6 +84,10 @@ 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=$(CONFIG_ZERO_ON_FREE) \
@@ -102,7 +106,8 @@ CPPFLAGS += \
     -DFREE_SLABS_QUARANTINE_RANDOM_LENGTH=$(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)
 
 $(OUT)/libhardened_malloc$(SUFFIX).so: $(OBJECTS) | $(OUT)
 	$(CC) $(CFLAGS) $(LDFLAGS) -shared $^ $(LDLIBS) -o $@

config/default.mk

@@ -20,3 +20,4 @@ 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

@@ -20,3 +20,4 @@ CONFIG_FREE_SLABS_QUARANTINE_RANDOM_LENGTH := 32
 CONFIG_CLASS_REGION_SIZE := 34359738368 # 32GiB
 CONFIG_N_ARENA := 4
 CONFIG_STATS := false
+CONFIG_SELF_INIT := true

h_malloc.c

@@ -1183,11 +1183,13 @@ static inline unsigned init(void) {
     return arena;
 }
 
+#if CONFIG_SELF_INIT
 // trigger early initialization to set up pthread_atfork and protect state as soon as possible
 COLD __attribute__((constructor(101))) static void trigger_early_init(void) {
     // avoid calling init directly to skip it if this isn't the malloc implementation
     h_free(h_malloc(16));
 }
+#endif
 
 // Returns 0 on overflow.
 static size_t get_large_size_class(size_t size) {