[PATCH 3.16.y-ckt 051/126] crypto: algif_hash - Only export and import on sockets with data

[Luis Henriques]

3.16.7-ckt21 -stable review patch.  If anyone has any objections, please let me know.

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

From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>

commit 4afa5f9617927453ac04b24b584f6c718dfb4f45 upstream.

The hash_accept call fails to work on sockets that have not received
any data.  For some algorithm implementations it may cause crashes.

This patch fixes this by ensuring that we only export and import on
sockets that have received data.

Reported-by: Harsh Jain <harshjain.prof@xxxxxxxxx>
Signed-off-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Tested-by: Stephan Mueller <smueller@xxxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 crypto/algif_hash.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 850246206b12..a68b56a368a8 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -192,9 +192,14 @@ static int hash_accept(struct socket *sock, struct socket *newsock, int flags)
 	struct sock *sk2;
 	struct alg_sock *ask2;
 	struct hash_ctx *ctx2;
+	bool more;
 	int err;
 
-	err = crypto_ahash_export(req, state);
+	lock_sock(sk);
+	more = ctx->more;
+	err = more ? crypto_ahash_export(req, state) : 0;
+	release_sock(sk);
+
 	if (err)
 		return err;
 
@@ -205,7 +210,10 @@ static int hash_accept(struct socket *sock, struct socket *newsock, int flags)
 	sk2 = newsock->sk;
 	ask2 = alg_sk(sk2);
 	ctx2 = ask2->private;
-	ctx2->more = 1;
+	ctx2->more = more;
+
+	if (!more)
+		return err;
 
 	err = crypto_ahash_import(&ctx2->req, state);
 	if (err) {
--
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