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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Antoine Tenart <antoine.tenart@free-electrons.com>,
        Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH 4.15 12/55] crypto: inside-secure - fix hash when length is a multiple of a block
Date:   Fri,  2 Feb 2018 17:58:30 +0100
Message-Id: <20180202140827.168066257@linuxfoundation.org>
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4.15-stable review patch.  If anyone has any objections, please let me know.

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

From: Antoine Tenart <antoine.tenart@free-electrons.com>

commit 809778e02cd45d0625439fee67688f655627bb3c upstream.

This patch fixes the hash support in the SafeXcel driver when the update
size is a multiple of a block size, and when a final call is made just
after with a size of 0. In such cases the driver should cache the last
block from the update to avoid handling 0 length data on the final call
(that's a hardware limitation).

Fixes: 1b44c5a60c13 ("crypto: inside-secure - add SafeXcel EIP197 crypto engine driver")
Signed-off-by: Antoine Tenart <antoine.tenart@free-electrons.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/crypto/inside-secure/safexcel_hash.c |   34 +++++++++++++++++++--------
 1 file changed, 24 insertions(+), 10 deletions(-)

--- a/drivers/crypto/inside-secure/safexcel_hash.c
+++ b/drivers/crypto/inside-secure/safexcel_hash.c
@@ -186,17 +186,31 @@ static int safexcel_ahash_send_req(struc
 	else
 		cache_len = queued - areq->nbytes;
 
-	/*
-	 * If this is not the last request and the queued data does not fit
-	 * into full blocks, cache it for the next send() call.
-	 */
-	extra = queued & (crypto_ahash_blocksize(ahash) - 1);
-	if (!req->last_req && extra) {
-		sg_pcopy_to_buffer(areq->src, sg_nents(areq->src),
-				   req->cache_next, extra, areq->nbytes - extra);
+	if (!req->last_req) {
+		/* If this is not the last request and the queued data does not
+		 * fit into full blocks, cache it for the next send() call.
+		 */
+		extra = queued & (crypto_ahash_blocksize(ahash) - 1);
+		if (!extra)
+			/* If this is not the last request and the queued data
+			 * is a multiple of a block, cache the last one for now.
+			 */
+			extra = queued - crypto_ahash_blocksize(ahash);
 
-		queued -= extra;
-		len -= extra;
+		if (extra) {
+			sg_pcopy_to_buffer(areq->src, sg_nents(areq->src),
+					   req->cache_next, extra,
+					   areq->nbytes - extra);
+
+			queued -= extra;
+			len -= extra;
+
+			if (!queued) {
+				*commands = 0;
+				*results = 0;
+				return 0;
+			}
+		}
 	}
 
 	spin_lock_bh(&priv->ring[ring].egress_lock);