From 3b8e97ab61624f4fbe8bb6a587f4da75cc3d988e Mon Sep 17 00:00:00 2001 From: Pauli Date: Wed, 22 Aug 2018 09:20:18 +1000 Subject: Zero memory in CRYPTO_secure_malloc. This commit destroys the free list pointers which would otherwise be present in the returned memory blocks. This in turn helps prevent information leakage from the secure memory area. Note: CRYPTO_secure_malloc is not guaranteed to return zeroed memory: before the secure memory system is initialised or if it isn't implemented. Reviewed-by: Tim Hudson Reviewed-by: Matthias St. Pierre (Merged from https://github.com/openssl/openssl/pull/7011) --- crypto/mem_sec.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-) (limited to 'crypto/mem_sec.c') diff --git a/crypto/mem_sec.c b/crypto/mem_sec.c index 959c63714f..c4190bed33 100644 --- a/crypto/mem_sec.c +++ b/crypto/mem_sec.c @@ -137,11 +137,12 @@ void *CRYPTO_secure_malloc(size_t num, const char *file, int line) void *CRYPTO_secure_zalloc(size_t num, const char *file, int line) { - void *ret = CRYPTO_secure_malloc(num, file, line); - - if (ret != NULL) - memset(ret, 0, num); - return ret; +#ifdef IMPLEMENTED + if (secure_mem_initialized) + /* CRYPTO_secure_malloc() zeroes allocations when it is implemented */ + return CRYPTO_secure_malloc(num, file, line); +#endif + return CRYPTO_zalloc(num, file, line); } void CRYPTO_secure_free(void *ptr, const char *file, int line) @@ -588,6 +589,9 @@ static void *sh_malloc(size_t size) OPENSSL_assert(WITHIN_ARENA(chunk)); + /* zero the free list header as a precaution against information leakage */ + memset(chunk, 0, sizeof(SH_LIST)); + return chunk; } @@ -620,6 +624,8 @@ static void sh_free(void *ptr) list--; + /* Zero the higher addressed block's free list pointers */ + memset(ptr > buddy ? ptr : buddy, 0, sizeof(SH_LIST)); if (ptr > buddy) ptr = buddy; -- cgit v1.2.3