[4.2.y-ckt stable] Patch "crypto: algif_hash - Only export and import on sockets with data" has been added to staging queue

[Kamal Mostafa]

This is a note to let you know that I have just added a patch titled

    crypto: algif_hash - Only export and import on sockets with data

to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue

This patch is scheduled to be released in version 4.2.8-ckt1.

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 4.2.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From 0f560d40664af22bf1171af9a556c082c728eb97 Mon Sep 17 00:00:00 2001
From: Herbert Xu <herbert at gondor.apana.org.au>
Date: Sun, 1 Nov 2015 17:11:19 +0800
Subject: crypto: algif_hash - Only export and import on sockets with data

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 at gmail.com>
Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
Tested-by: Stephan Mueller <smueller at chronox.de>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 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 1396ad0..b4c24fe 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -181,9 +181,14 @@ 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;

@@ -194,7 +199,10 @@ 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) {
--
1.9.1