crypto: algif_skcipher - sendmsg SG marking is off by one

We mark the end of the SG list in sendmsg and sendpage and unmark
it on the next send call.  Unfortunately the unmarking in sendmsg
is off-by-one, leading to an SG list that is too short.

Fixes: 0f477b655a52 ("crypto: algif - Mark sgl end at the end of data")
Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 2 insertions, 1 deletions

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index df86fb47c3ae..a81c10faf9c4 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -392,7 +392,8 @@ static int skcipher_sendmsg(struct socket *sock, struct msghdr *msg,
 
                 sgl = list_entry(ctx->tsgl.prev, struct skcipher_sg_list, list);
                 sg = sgl->sg;
-                sg_unmark_end(sg + sgl->cur);
+                if (sgl->cur)
+                        sg_unmark_end(sg + sgl->cur - 1);
                 do {
                         i = sgl->cur;
                         plen = min_t(size_t, len, PAGE_SIZE);