Having a zero length sg doesn't mean it is the end of the sg list. This
case happens when calculating HMAC of IPSec packet.

Signed-off-by: Leilei Zhao <leilei.z...@atmel.com>
Signed-off-by: Ludovic Desroches <ludovic.desroc...@atmel.com>
Acked-by: Nicolas Ferre <nicolas.fe...@atmel.com>
---
 drivers/crypto/atmel-sha.c |   16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/atmel-sha.c b/drivers/crypto/atmel-sha.c
index b471bbe..9fb8af1 100644
--- a/drivers/crypto/atmel-sha.c
+++ b/drivers/crypto/atmel-sha.c
@@ -163,8 +163,20 @@ static size_t atmel_sha_append_sg(struct atmel_sha_reqctx 
*ctx)
                count = min(ctx->sg->length - ctx->offset, ctx->total);
                count = min(count, ctx->buflen - ctx->bufcnt);
 
-               if (count <= 0)
-                       break;
+               if (count <= 0) {
+                       /*
+                       * Check if count <= 0 because the buffer is full or
+                       * because the sg length is 0. In the latest case,
+                       * check if there is another sg in the list, a 0 length
+                       * sg doesn't necessarily mean the end of the sg list.
+                       */
+                       if ((ctx->sg->length == 0) && !sg_is_last(ctx->sg)) {
+                               ctx->sg = sg_next(ctx->sg);
+                               continue;
+                       } else {
+                               break;
+                       }
+               }
 
                scatterwalk_map_and_copy(ctx->buffer + ctx->bufcnt, ctx->sg,
                        ctx->offset, count, 0);
-- 
1.7.9.5

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