[PATCH 3.16.y-ckt 28/94] crypto: ahash - ensure statesize is non-zero

[Luis Henriques]

3.16.7-ckt20 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Russell King <rmk+kernel at arm.linux.org.uk>

commit 8996eafdcbad149ac0f772fb1649fbb75c482a6a upstream.

Unlike shash algorithms, ahash drivers must implement export
and import as their descriptors may contain hardware state and
cannot be exported as is.  Unfortunately some ahash drivers did
not provide them and end up causing crashes with algif_hash.

This patch adds a check to prevent these drivers from registering
ahash algorithms until they are fixed.

Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 crypto/ahash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index f2a5d8f656ff..d3e86a46ecea 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -537,7 +537,8 @@ static int ahash_prepare_alg(struct ahash_alg *alg)
 	struct crypto_alg *base = &alg->halg.base;
 
 	if (alg->halg.digestsize > PAGE_SIZE / 8 ||
-	    alg->halg.statesize > PAGE_SIZE / 8)
+	    alg->halg.statesize > PAGE_SIZE / 8 ||
+	    alg->halg.statesize == 0)
 		return -EINVAL;
 
 	base->cra_type = &crypto_ahash_type;