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add unaligned free check for small allocations

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This commit is contained in:
Daniel Micay 2018-08-24 02:55:53 -04:00
parent 2aee424b7b
commit 7a86b67778
1 changed files with 12 additions and 3 deletions
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15
malloc.c
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@ -276,6 +276,10 @@ static struct slab_metadata *get_metadata(struct size_class *c, size_t slab_size
return c->slab_info + index; return c->slab_info + index;
} }
static void *slot_pointer(size_t size, void *slab, size_t slot) {
return (char *)slab + slot * size;
}
static void *slab_allocate(size_t requested_size) { static void *slab_allocate(size_t requested_size) {
struct size_info info = get_size_info(requested_size); struct size_info info = get_size_info(requested_size);
size_t size = info.size; size_t size = info.size;
@ -347,7 +351,7 @@ static void *slab_allocate(size_t requested_size) {
} }
void *slab = get_slab(c, slab_size, metadata); void *slab = get_slab(c, slab_size, metadata);
void *p = (char *)slab + slot * size; void *p = slot_pointer(size, slab, slot);
pthread_mutex_unlock(&c->mutex); pthread_mutex_unlock(&c->mutex);
return p; return p;
@ -373,6 +377,13 @@ static void slab_free(void *p) {
pthread_mutex_lock(&c->mutex); pthread_mutex_lock(&c->mutex);
struct slab_metadata *metadata = get_metadata(c, slab_size, p); struct slab_metadata *metadata = get_metadata(c, slab_size, p);
void *slab = get_slab(c, slab_size, metadata);
size_t slot = ((char *)p - (char *)slab) / size;
if (slot_pointer(size, slab, slot) != p) {
fatal_error("invalid unaligned free");
}
if (!has_free_slots(slots, metadata)) { if (!has_free_slots(slots, metadata)) {
metadata->next = c->partial_slabs; metadata->next = c->partial_slabs;
metadata->prev = NULL; metadata->prev = NULL;
@ -383,8 +394,6 @@ static void slab_free(void *p) {
c->partial_slabs = metadata; c->partial_slabs = metadata;
} }
void *slab = get_slab(c, slab_size, metadata);
size_t slot = ((char *)p - (char *)slab) / size;
if (!get_slot(metadata, slot)) { if (!get_slot(metadata, slot)) {
fatal_error("double free"); fatal_error("double free");
} }