From 8996eafdcbad149ac0f772fb1649fbb75c482a6a Mon Sep 17 00:00:00 2001
From: Russell King <rmk+kernel@arm.linux.org.uk>
Date: Fri, 9 Oct 2015 20:43:33 +0100
Subject: [PATCH] crypto: ahash - ensure statesize is non-zero

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.

Cc: stable@vger.kernel.org
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---
 crypto/ahash.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/crypto/ahash.c b/crypto/ahash.c
index 8acb886032ae7..9c1dc8d6106a8 100644
--- a/crypto/ahash.c
+++ b/crypto/ahash.c
@@ -544,7 +544,8 @@ 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;
-- 
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