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Fix infinite loops in secure memory allocation.

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Issue 1:

sh.bittable_size is a size_t but i is and int, which can result in
freelist == -1 if sh.bittable_size exceeds an int.

This seems to result in an OPENSSL_assert due to invalid allocation
size, so maybe that is "ok."

Worse, if sh.bittable_size is exactly 1<<31, then this becomes an
infinite loop (because 1<<31 is a negative int, so it can be shifted
right forever and sticks at -1).

Issue 2:

CRYPTO_secure_malloc_init() sets secure_mem_initialized=1 even when
sh_init() returns 0.

If sh_init() fails, we end up with secure_mem_initialized=1 but
sh.minsize=0. If you then call secure_malloc(), which then calls,
sh_malloc(), this then enters an infite loop since 0 << anything will
never be larger than size.

Issue 3:

That same sh_malloc loop will loop forever for a size greater
than size_t/2 because i will proceed (assuming sh.minsize=16):
i=16, 32, 64, ..., size_t/8, size_t/4, size_t/2, 0, 0, 0, 0, ....
This sequence will never be larger than "size".

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3449)
This commit is contained in:
Todd Short 2017-05-11 15:48:10 -04:00 committed by Richard Levitte
parent b57f0c598b
commit 7031ddac94
2 changed files with 33 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
crypto/mem_sec.c
View file

@ -73,8 +73,12 @@ int CRYPTO_secure_malloc_init(size_t size, int minsize)
sec_malloc_lock = CRYPTO_THREAD_lock_new();
if (sec_malloc_lock == NULL)
return 0;
ret = sh_init(size, minsize);
secure_mem_initialized = 1;
if ((ret = sh_init(size, minsize)) != 0) {
secure_mem_initialized = 1;
} else {
CRYPTO_THREAD_lock_free(sec_malloc_lock);
sec_malloc_lock = NULL;
}
}
return ret;
@ -90,6 +94,7 @@ int CRYPTO_secure_malloc_done()
sh_done();
secure_mem_initialized = 0;
CRYPTO_THREAD_lock_free(sec_malloc_lock);
sec_malloc_lock = NULL;
return 1;
}
#endif /* IMPLEMENTED */
@ -341,7 +346,8 @@ static void sh_remove_from_list(char *ptr)
static int sh_init(size_t size, int minsize)
{
int i, ret;
int ret;
size_t i;
size_t pgsize;
size_t aligned;
@ -498,6 +504,9 @@ static void *sh_malloc(size_t size)
size_t i;
char *chunk;
if (size > sh.arena_size)
return NULL;
list = sh.freelist_size - 1;
for (i = sh.minsize; i < size; i <<= 1)
list--;

21
test/secmemtest.c
View file

@ -61,6 +61,27 @@ static int test_sec_mem(void)
|| !TEST_true(CRYPTO_secure_malloc_done())
|| !TEST_false(CRYPTO_secure_malloc_initialized()))
goto end;
TEST_info("Possible infinite loop: allocate more than available");
if (!TEST_true(CRYPTO_secure_malloc_init(32768, 16)))
goto end;
TEST_ptr_null(OPENSSL_secure_malloc((size_t)-1));
TEST_true(CRYPTO_secure_malloc_done());
TEST_info("Possible infinite loop: small arena");
if (!TEST_false(CRYPTO_secure_malloc_init(16, 16)))
goto end;
TEST_false(CRYPTO_secure_malloc_initialized());
TEST_ptr_null(OPENSSL_secure_malloc((size_t)-1));
TEST_true(CRYPTO_secure_malloc_done());
if (sizeof(size_t) > 4) {
TEST_info("Possible infinite loop: 1<<31 limit");
if (!TEST_true(CRYPTO_secure_malloc_init((size_t)1<<34, (size_t)1<<4) != 0))
goto end;
TEST_true(CRYPTO_secure_malloc_done());
}
/* this can complete - it was not really secure */
testresult = 1;
end: