[PATCH 3.16.y-ckt 130/180] crypto: algif_skcipher - Load TX SG list after waiting

[Luis Henriques]

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Herbert Xu <herbert at gondor.apana.org.au>

commit 4f0414e54e4d1893c6f08260693f8ef84c929293 upstream.

We need to load the TX SG list in sendmsg(2) after waiting for
incoming data, not before.

Reported-by: Dmitry Vyukov <dvyukov at google.com>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Tested-by: Dmitry Vyukov <dvyukov at google.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 crypto/algif_skcipher.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 83187f497c7c..bb68c92e68c6 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -441,13 +441,6 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
 		char __user *from = iov->iov_base;
 
 		while (seglen) {
-			sgl = list_first_entry(&ctx->tsgl,
-					       struct skcipher_sg_list, list);
-			sg = sgl->sg;
-
-			while (!sg->length)
-				sg++;
-
 			used = ctx->used;
 			if (!used) {
 				err = skcipher_wait_for_data(sk, flags);
@@ -469,6 +462,13 @@ static int skcipher_recvmsg(struct kiocb *unused, struct socket *sock,
 			if (!used)
 				goto free;
 
+			sgl = list_first_entry(&ctx->tsgl,
+					       struct skcipher_sg_list, list);
+			sg = sgl->sg;
+
+			while (!sg->length)
+				sg++;
+
 			ablkcipher_request_set_crypt(&ctx->req, sg,
 						     ctx->rsgl.sg, used,
 						     ctx->iv);