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Tell ASan about the OPENSSL_malloc prefix.

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OpenSSL's BN_mul function had a single-word buffer underflow (see
576129cd72ae054d246221f111aabf42b9c6d76d). We already independently
fixed this but, if we hadn't, ASan wouldn't have noticed because of
OPENSSL_malloc.

ASan has runtime hooks we can call to make it more accurate.

Change-Id: Ifc9c3837ece2bc456c5bdc960be707d7b1759904
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/35165
Reviewed-by: Adam Langley <agl@google.com>
This commit is contained in:
David Benjamin 2019-02-26 22:13:28 -06:00 committed by Adam Langley
parent 8d685ec867
commit da8bb847fd
1 changed files with 12 additions and 0 deletions
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12
crypto/mem.c
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@ -71,6 +71,14 @@ OPENSSL_MSVC_PRAGMA(warning(pop))
#define OPENSSL_MALLOC_PREFIX 8
#if defined(OPENSSL_ASAN)
void __asan_poison_memory_region(const volatile void *addr, size_t size);
void __asan_unpoison_memory_region(const volatile void *addr, size_t size);
#else
static void __asan_poison_memory_region(const void *addr, size_t size) {}
static void __asan_unpoison_memory_region(const void *addr, size_t size) {}
#endif
#if defined(__GNUC__) || defined(__clang__)
// sdallocx is a sized |free| function. By passing the size (which we happen to
// always know in BoringSSL), the malloc implementation can save work. We cannot
@ -99,6 +107,7 @@ void *OPENSSL_malloc(size_t size) {
*(size_t *)ptr = size;
__asan_poison_memory_region(ptr, OPENSSL_MALLOC_PREFIX);
return ((uint8_t *)ptr) + OPENSSL_MALLOC_PREFIX;
}
@ -108,6 +117,7 @@ void OPENSSL_free(void *orig_ptr) {
}
void *ptr = ((uint8_t *)orig_ptr) - OPENSSL_MALLOC_PREFIX;
__asan_unpoison_memory_region(ptr, OPENSSL_MALLOC_PREFIX);
size_t size = *(size_t *)ptr;
OPENSSL_cleanse(ptr, size + OPENSSL_MALLOC_PREFIX);
@ -120,7 +130,9 @@ void *OPENSSL_realloc(void *orig_ptr, size_t new_size) {
}
void *ptr = ((uint8_t *)orig_ptr) - OPENSSL_MALLOC_PREFIX;
__asan_unpoison_memory_region(ptr, OPENSSL_MALLOC_PREFIX);
size_t old_size = *(size_t *)ptr;
__asan_poison_memory_region(ptr, OPENSSL_MALLOC_PREFIX);
void *ret = OPENSSL_malloc(new_size);
if (ret == NULL) {