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hardened_malloc
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make non-out-of-memory mprotect errors fatal

pull/50/head
Daniel Micay 2018-08-28 22:21:38 -04:00
parent 19c46d16f1
commit 705b6a4f8d
1 changed files with 14 additions and 6 deletions
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20
malloc.c
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@ -44,6 +44,14 @@ static int memory_unmap(void *ptr, size_t size) {
return ret; return ret;
} }
static int memory_protect(void *ptr, size_t size, int prot) {
int ret = mprotect(ptr, size, prot);
if (ret && errno != ENOMEM) {
fatal_error("non-ENOMEM mprotect failure");
}
return ret;
}
static void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect) { static void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotect) {
usable_size = PAGE_CEILING(usable_size); usable_size = PAGE_CEILING(usable_size);
@ -56,7 +64,7 @@ static void *allocate_pages(size_t usable_size, size_t guard_size, bool unprotec
return NULL; return NULL;
} }
void *usable = (char *)real + guard_size; void *usable = (char *)real + guard_size;
if (unprotect && mprotect(usable, usable_size, PROT_READ|PROT_WRITE)) { if (unprotect && memory_protect(usable, usable_size, PROT_READ|PROT_WRITE)) {
memory_unmap(real, real_size); memory_unmap(real, real_size);
return NULL; return NULL;
} }
@ -93,7 +101,7 @@ static void *allocate_pages_aligned(size_t usable_size, size_t alignment, size_t
size_t trail_size = alloc_size - lead_size - usable_size; size_t trail_size = alloc_size - lead_size - usable_size;
void *base = (char *)usable + lead_size; void *base = (char *)usable + lead_size;
if (mprotect(base, usable_size, PROT_READ|PROT_WRITE)) { if (memory_protect(base, usable_size, PROT_READ|PROT_WRITE)) {
memory_unmap(real, real_alloc_size); memory_unmap(real, real_alloc_size);
return NULL; return NULL;
} }
@ -214,7 +222,7 @@ static struct slab_metadata *alloc_metadata(struct size_class *c, size_t slab_si
if (allocate > metadata_max) { if (allocate > metadata_max) {
allocate = metadata_max; allocate = metadata_max;
} }
if (mprotect(c->slab_info, allocate * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) { if (memory_protect(c->slab_info, allocate * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) {
return NULL; return NULL;
} }
c->metadata_allocated = allocate; c->metadata_allocated = allocate;
@ -344,7 +352,7 @@ static inline void *slab_allocate(size_t requested_size) {
} }
void *slab = get_slab(c, slab_size, metadata); void *slab = get_slab(c, slab_size, metadata);
if (requested_size != 0 && mprotect(slab, slab_size, PROT_READ|PROT_WRITE)) { if (requested_size != 0 && memory_protect(slab, slab_size, PROT_READ|PROT_WRITE)) {
c->metadata_count--; c->metadata_count--;
pthread_mutex_unlock(&c->mutex); pthread_mutex_unlock(&c->mutex);
return NULL; return NULL;
@ -647,14 +655,14 @@ COLD static void init_slow_path(void) {
fatal_error("failed to allocate slab metadata"); fatal_error("failed to allocate slab metadata");
} }
c->metadata_allocated = PAGE_SIZE / sizeof(struct slab_metadata); c->metadata_allocated = PAGE_SIZE / sizeof(struct slab_metadata);
if (mprotect(c->slab_info, c->metadata_allocated * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) { if (memory_protect(c->slab_info, c->metadata_allocated * sizeof(struct slab_metadata), PROT_READ|PROT_WRITE)) {
fatal_error("failed to allocate initial slab info"); fatal_error("failed to allocate initial slab info");
} }
} }
atomic_store_explicit(&ro.initialized, true, memory_order_release); atomic_store_explicit(&ro.initialized, true, memory_order_release);
if (mprotect(&ro, sizeof(ro), PROT_READ)) { if (memory_protect(&ro, sizeof(ro), PROT_READ)) {
fatal_error("failed to protect allocator data"); fatal_error("failed to protect allocator data");
} }