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) --- test/secmemtest.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) (limited to 'test') diff --git a/test/secmemtest.c b/test/secmemtest.c index 9efa2c89d5..2795abb546 100644 --- a/test/secmemtest.c +++ b/test/secmemtest.c @@ -129,8 +129,52 @@ static int test_sec_mem(void) #endif } +static int test_sec_mem_clear(void) +{ +#if defined(OPENSSL_SYS_LINUX) || defined(OPENSSL_SYS_UNIX) + const int size = 64; + unsigned char *p = NULL; + int i, res = 0; + + if (!TEST_true(CRYPTO_secure_malloc_init(4096, 32)) + || !TEST_ptr(p = OPENSSL_secure_malloc(size))) + goto err; + + for (i = 0; i < size; i++) + if (!TEST_uchar_eq(p[i], 0)) + goto err; + + for (i = 0; i < size; i++) + p[i] = (unsigned char)(i + ' ' + 1); + + OPENSSL_secure_free(p); + + /* + * A deliberate use after free here to verify that the memory has been + * cleared properly. Since secure free doesn't return the memory to + * libc's memory pool, it technically isn't freed. However, the header + * bytes have to be skipped and these consist of two pointers in the + * current implementation. + */ + for (i = sizeof(void *) * 2; i < size; i++) + if (!TEST_uchar_eq(p[i], 0)) + return 0; + + res = 1; + p = NULL; + +err: + OPENSSL_secure_free(p); + CRYPTO_secure_malloc_done(); + return res; +#else + return 1; +#endif +} + int setup_tests(void) { ADD_TEST(test_sec_mem); + ADD_TEST(test_sec_mem_clear); return 1; } -- cgit v1.2.3