crypto: atmel-sha - fix sg list management

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.zhao@atmel.com>
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 14 insertions, 2 deletions

diff --git a/drivers/crypto/atmel-sha.c b/drivers/crypto/atmel-sha.c
index 215858a829c3..b093862eebf3 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);