From:   Corentin Labbe <clabbe.montjoie@gmail.com>
To:     davem@davemloft.net, herbert@gondor.apana.org.au,
        maxime.ripard@bootlin.com, wens@csie.org
Cc:     linux-arm-kernel@lists.infradead.org, linux-crypto@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-sunxi@googlegroups.com,
        ebiggers@kernel.org, Corentin Labbe <clabbe.montjoie@gmail.com>
Subject: [PATCH 3/4] crypto: sun4i-ss: Fix invalid calculation of hash end
Date:   Thu, 18 Apr 2019 10:17:34 +0200
Message-Id: <20190418081735.19002-4-clabbe.montjoie@gmail.com>
In-Reply-To: <20190418081735.19002-1-clabbe.montjoie@gmail.com>
References: <20190418081735.19002-1-clabbe.montjoie@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-crypto-owner@vger.kernel.org
Precedence: bulk

When nbytes < 4, end is wronlgy set to a negative value which, due to
uint, is then interpreted to a large value leading to a deadlock in the
following code.

This patch fix this problem.

Fixes: 6298e948215f ("crypto: sunxi-ss - Add Allwinner Security System crypto accelerator")
Signed-off-by: Corentin Labbe <clabbe.montjoie@gmail.com>
---
 drivers/crypto/sunxi-ss/sun4i-ss-hash.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/crypto/sunxi-ss/sun4i-ss-hash.c b/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
index a4b5ff2b72f8..f6936bb3b7be 100644
--- a/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
+++ b/drivers/crypto/sunxi-ss/sun4i-ss-hash.c
@@ -240,7 +240,10 @@ static int sun4i_hash(struct ahash_request *areq)
 		}
 	} else {
 		/* Since we have the flag final, we can go up to modulo 4 */
-		end = ((areq->nbytes + op->len) / 4) * 4 - op->len;
+		if (areq->nbytes < 4)
+			end = 0;
+		else
+			end = ((areq->nbytes + op->len) / 4) * 4 - op->len;
 	}
 
 	/* TODO if SGlen % 4 and !op->len then DMA */
-- 
2.21.0