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harden checks for uninitialized usage

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This commit is contained in:
Daniel Micay 2020-10-02 15:04:41 -04:00
parent b9ebf47c7c
commit 178d4f320f
1 changed files with 21 additions and 21 deletions
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42
h_malloc.c
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@ -68,8 +68,8 @@ static const unsigned thread_arena = 0;
static union { static union {
struct { struct {
void *_Atomic slab_region_start; void *slab_region_start;
void *slab_region_end; void *_Atomic slab_region_end;
struct size_class *size_class_metadata[N_ARENA]; struct size_class *size_class_metadata[N_ARENA];
struct region_allocator *region_allocator; struct region_allocator *region_allocator;
struct region_metadata *regions[2]; struct region_metadata *regions[2];
@ -80,8 +80,8 @@ static union {
char padding[PAGE_SIZE]; char padding[PAGE_SIZE];
} ro __attribute__((aligned(PAGE_SIZE))); } ro __attribute__((aligned(PAGE_SIZE)));
static inline void *get_slab_region_start() { static inline void *get_slab_region_end() {
return atomic_load_explicit(&ro.slab_region_start, memory_order_acquire); return atomic_load_explicit(&ro.slab_region_end, memory_order_acquire);
} }
#define SLAB_METADATA_COUNT #define SLAB_METADATA_COUNT
@ -1039,7 +1039,7 @@ static void post_fork_child(void) {
} }
static inline bool is_init(void) { static inline bool is_init(void) {
return get_slab_region_start() != NULL; return get_slab_region_end() != NULL;
} }
static inline void enforce_init(void) { static inline void enforce_init(void) {
@ -1098,12 +1098,12 @@ COLD static void init_slow_path(void) {
fatal_error("failed to unprotect memory for regions table"); fatal_error("failed to unprotect memory for regions table");
} }
void *slab_region_start = memory_map(slab_region_size); ro.slab_region_start = memory_map(slab_region_size);
if (slab_region_start == NULL) { if (ro.slab_region_start == NULL) {
fatal_error("failed to allocate slab region"); fatal_error("failed to allocate slab region");
} }
ro.slab_region_end = (char *)slab_region_start + slab_region_size; void *slab_region_end = (char *)ro.slab_region_start + slab_region_size;
memory_set_name(slab_region_start, slab_region_size, "malloc slab region gap"); memory_set_name(ro.slab_region_start, slab_region_size, "malloc slab region gap");
for (unsigned arena = 0; arena < N_ARENA; arena++) { for (unsigned arena = 0; arena < N_ARENA; arena++) {
ro.size_class_metadata[arena] = allocator_state->size_class_metadata[arena]; ro.size_class_metadata[arena] = allocator_state->size_class_metadata[arena];
@ -1115,7 +1115,7 @@ COLD static void init_slow_path(void) {
size_t bound = (REAL_CLASS_REGION_SIZE - CLASS_REGION_SIZE) / PAGE_SIZE - 1; size_t bound = (REAL_CLASS_REGION_SIZE - CLASS_REGION_SIZE) / PAGE_SIZE - 1;
size_t gap = (get_random_u64_uniform(rng, bound) + 1) * PAGE_SIZE; size_t gap = (get_random_u64_uniform(rng, bound) + 1) * PAGE_SIZE;
c->class_region_start = (char *)slab_region_start + ARENA_SIZE * arena + REAL_CLASS_REGION_SIZE * class + gap; c->class_region_start = (char *)ro.slab_region_start + ARENA_SIZE * arena + REAL_CLASS_REGION_SIZE * class + gap;
label_slab(c->class_region_start, CLASS_REGION_SIZE, class); label_slab(c->class_region_start, CLASS_REGION_SIZE, class);
size_t size = size_classes[class]; size_t size = size_classes[class];
@ -1131,7 +1131,7 @@ COLD static void init_slow_path(void) {
deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE); deallocate_pages(rng, sizeof(struct random_state), PAGE_SIZE);
atomic_store_explicit(&ro.slab_region_start, slab_region_start, memory_order_release); atomic_store_explicit(&ro.slab_region_end, slab_region_end, memory_order_release);
if (memory_protect_ro(&ro, sizeof(ro))) { if (memory_protect_ro(&ro, sizeof(ro))) {
fatal_error("failed to protect allocator data"); fatal_error("failed to protect allocator data");
@ -1355,7 +1355,7 @@ EXPORT void *h_realloc(void *old, size_t size) {
} }
size_t old_size; size_t old_size;
if (old >= get_slab_region_start() && old < ro.slab_region_end) { if (old < get_slab_region_end() && old >= ro.slab_region_start) {
old_size = slab_usable_size(old); old_size = slab_usable_size(old);
if (size <= MAX_SLAB_SIZE_CLASS && get_size_info(size).size == old_size) { if (size <= MAX_SLAB_SIZE_CLASS && get_size_info(size).size == old_size) {
return old; return old;
@ -1531,7 +1531,7 @@ EXPORT void h_free(void *p) {
return; return;
} }
if (p >= get_slab_region_start() && p < ro.slab_region_end) { if (p < get_slab_region_end() && p >= ro.slab_region_start) {
thread_unseal_metadata(); thread_unseal_metadata();
deallocate_small(p, NULL); deallocate_small(p, NULL);
thread_seal_metadata(); thread_seal_metadata();
@ -1552,7 +1552,7 @@ EXPORT void h_free_sized(void *p, size_t expected_size) {
return; return;
} }
if (p >= get_slab_region_start() && p < ro.slab_region_end) { if (p < get_slab_region_end() && p >= ro.slab_region_start) {
thread_unseal_metadata(); thread_unseal_metadata();
expected_size = get_size_info(adjust_size_for_canaries(expected_size)).size; expected_size = get_size_info(adjust_size_for_canaries(expected_size)).size;
deallocate_small(p, &expected_size); deallocate_small(p, &expected_size);
@ -1615,7 +1615,7 @@ EXPORT size_t h_malloc_usable_size(H_MALLOC_USABLE_SIZE_CONST void *p) {
enforce_init(); enforce_init();
thread_unseal_metadata(); thread_unseal_metadata();
if (p >= get_slab_region_start() && p < ro.slab_region_end) { if (p < get_slab_region_end() && p >= ro.slab_region_start) {
memory_corruption_check_small(p); memory_corruption_check_small(p);
thread_seal_metadata(); thread_seal_metadata();
@ -1643,8 +1643,8 @@ EXPORT size_t h_malloc_object_size(void *p) {
thread_unseal_metadata(); thread_unseal_metadata();
void *slab_region_start = get_slab_region_start(); void *slab_region_end = get_slab_region_end();
if (p >= slab_region_start && p < ro.slab_region_end) { if (p < slab_region_end && p >= ro.slab_region_start) {
struct slab_size_class_info size_class_info = slab_size_class(p); struct slab_size_class_info size_class_info = slab_size_class(p);
size_t class = size_class_info.class; size_t class = size_class_info.class;
size_t size_class = size_classes[class]; size_t size_class = size_classes[class];
@ -1677,7 +1677,7 @@ EXPORT size_t h_malloc_object_size(void *p) {
return size ? size - canary_size - offset : 0; return size ? size - canary_size - offset : 0;
} }
if (unlikely(slab_region_start == NULL)) { if (unlikely(slab_region_end == NULL)) {
return SIZE_MAX; return SIZE_MAX;
} }
@ -1696,13 +1696,13 @@ EXPORT size_t h_malloc_object_size_fast(void *p) {
return 0; return 0;
} }
void *slab_region_start = get_slab_region_start(); void *slab_region_end = get_slab_region_end();
if (p >= slab_region_start && p < ro.slab_region_end) { if (p < slab_region_end && p >= ro.slab_region_start) {
size_t size = slab_usable_size(p); size_t size = slab_usable_size(p);
return size ? size - canary_size : 0; return size ? size - canary_size : 0;
} }
if (unlikely(slab_region_start == NULL)) { if (unlikely(slab_region_end == NULL)) {
return 0; return 0;
} }