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get rid of canary_value when canaries are disabled

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This commit is contained in:
Daniel Micay 2022-01-03 17:56:57 -05:00
parent 346529574d
commit 5f32942263
1 changed files with 28 additions and 22 deletions
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50
h_malloc.c
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@ -92,7 +92,9 @@ struct slab_metadata {
u64 bitmap[4];
struct slab_metadata *next;
struct slab_metadata *prev;
#if SLAB_CANARY
u64 canary_value;
#endif
#ifdef SLAB_METADATA_COUNT
u16 count;
#endif
@ -450,16 +452,30 @@ static void write_after_free_check(const char *p, size_t size) {
}
}
static const u64 canary_mask = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ ?
0xffffffffffffff00UL :
0x00ffffffffffffffUL;
static void set_slab_canary_value(UNUSED struct slab_metadata *metadata, UNUSED struct random_state *rng) {
#if SLAB_CANARY
static const u64 canary_mask = __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ ?
0xffffffffffffff00UL :
0x00ffffffffffffffUL;
static void set_canary(const struct slab_metadata *metadata, void *p, size_t size) {
memcpy((char *)p + size - canary_size, &metadata->canary_value, canary_size);
metadata->canary_value = get_random_u64(rng) & canary_mask;
#endif
}
static u64 get_random_canary(struct random_state *rng) {
return get_random_u64(rng) & canary_mask;
static void set_canary(UNUSED const struct slab_metadata *metadata, UNUSED void *p, UNUSED size_t size) {
#if SLAB_CANARY
memcpy((char *)p + size - canary_size, &metadata->canary_value, canary_size);
#endif
}
static void check_canary(UNUSED const struct slab_metadata *metadata, UNUSED const void *p, UNUSED size_t size) {
#if SLAB_CANARY
u64 canary_value;
memcpy(&canary_value, (const char *)p + size - canary_size, canary_size);
if (unlikely(canary_value != metadata->canary_value)) {
fatal_error("canary corrupted");
}
#endif
}
static inline void stats_small_allocate(UNUSED struct size_class *c, UNUSED size_t size) {
@ -525,7 +541,7 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
if (c->free_slabs_head != NULL) {
struct slab_metadata *metadata = c->free_slabs_head;
metadata->canary_value = get_random_canary(&c->rng);
set_slab_canary_value(metadata, &c->rng);
void *slab = get_slab(c, slab_size, metadata);
if (requested_size && memory_protect_rw(slab, slab_size)) {
@ -561,7 +577,7 @@ static inline void *allocate_small(unsigned arena, size_t requested_size) {
mutex_unlock(&c->lock);
return NULL;
}
metadata->canary_value = get_random_canary(&c->rng);
set_slab_canary_value(metadata, &c->rng);
c->partial_slabs = slots > 1 ? metadata : NULL;
void *slab = get_slab(c, slab_size, metadata);
@ -673,13 +689,7 @@ static inline void deallocate_small(void *p, const size_t *expected_size) {
}
if (!is_zero_size) {
if (SLAB_CANARY) {
u64 canary_value;
memcpy(&canary_value, (char *)p + size - canary_size, canary_size);
if (unlikely(canary_value != metadata->canary_value)) {
fatal_error("canary corrupted");
}
}
check_canary(metadata, p, size);
if (ZERO_ON_FREE) {
memset(p, 0, size - canary_size);
@ -1589,12 +1599,8 @@ static inline void memory_corruption_check_small(const void *p) {
fatal_error("invalid malloc_usable_size");
}
if (!is_zero_size && SLAB_CANARY) {
u64 canary_value;
memcpy(&canary_value, (const char *)p + size - canary_size, canary_size);
if (unlikely(canary_value != metadata->canary_value)) {
fatal_error("canary corrupted");
}
if (!is_zero_size) {
check_canary(metadata, p, size);
}
#if SLAB_QUARANTINE