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protect region allocator state with random guards

This commit is contained in:
Daniel Micay 2018-10-14 22:41:17 -04:00
parent 124d958da1
commit fde9fc2ece
1 changed files with 13 additions and 2 deletions
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15
malloc.c
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@ -753,7 +753,16 @@ COLD static void init_slow_path(void) {
fatal_error("page size mismatch");
}
ro.region_allocator = allocate_pages(sizeof(struct region_allocator), PAGE_SIZE, true);
struct random_state *rng = allocate_pages(sizeof(struct random_state), PAGE_SIZE, true);
if (rng == NULL) {
fatal_error("failed to allocate init rng");
}
random_state_init(rng);
size_t metadata_guard_size =
(get_random_u64_uniform(rng, REAL_CLASS_REGION_SIZE / PAGE_SIZE) + 1) * PAGE_SIZE;
ro.region_allocator = allocate_pages(sizeof(struct region_allocator), metadata_guard_size, true);
if (ro.region_allocator == NULL) {
fatal_error("failed to allocate region allocator state");
}
@ -791,7 +800,7 @@ COLD static void init_slow_path(void) {
random_state_init(&c->rng);
size_t bound = (REAL_CLASS_REGION_SIZE - CLASS_REGION_SIZE) / PAGE_SIZE - 1;
size_t gap = (get_random_u64_uniform(&c->rng, bound) + 1) * PAGE_SIZE;
size_t gap = (get_random_u64_uniform(rng, bound) + 1) * PAGE_SIZE;
c->class_region_start = (char *)ro.slab_region_start + REAL_CLASS_REGION_SIZE * class + gap;
size_t size = size_classes[class];
@ -812,6 +821,8 @@ COLD static void init_slow_path(void) {
}
}
deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE);
atomic_store_explicit(&ro.initialized, true, memory_order_release);
if (memory_protect_ro(&ro, sizeof(ro))) {