[PATCH] crypto: testmgr - add guard to dst buffer for ahash_export
From: Jan Stancek <jstancek@redhat.com>
Date: 2016-09-28 14:38:52
Also in:
lkml
Subsystem:
crypto api, the rest · Maintainers:
Herbert Xu, "David S. Miller", Linus Torvalds
Add a guard to 'state' buffer and warn if its consistency after call to crypto_ahash_export() changes, so that any write that goes beyond advertised statesize (and thus causing potential memory corruption [1]) is more visible. [1] https://marc.info/?l=linux-crypto-vger&m=147467656516085 Signed-off-by: Jan Stancek <jstancek@redhat.com> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Marcelo Cerri <redacted> --- crypto/testmgr.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/crypto/testmgr.c b/crypto/testmgr.c
index 5c9d5a5e7b65..96343bcae01e 100644
--- a/crypto/testmgr.c
+++ b/crypto/testmgr.c@@ -209,16 +209,19 @@ static int ahash_partial_update(struct ahash_request **preq, char *state; struct ahash_request *req; int statesize, ret = -EINVAL; + const char guard[] = { 0x00, 0xba, 0xad, 0x00 }; req = *preq; statesize = crypto_ahash_statesize( crypto_ahash_reqtfm(req)); - state = kmalloc(statesize, GFP_KERNEL); + state = kmalloc(statesize + sizeof(guard), GFP_KERNEL); if (!state) { pr_err("alt: hash: Failed to alloc state for %s\n", algo); goto out_nostate; } + memcpy(state + statesize, guard, sizeof(guard)); ret = crypto_ahash_export(req, state); + WARN_ON(memcmp(state + statesize, guard, sizeof(guard))); if (ret) { pr_err("alt: hash: Failed to export() for %s\n", algo); goto out;
--
1.8.3.1