From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 15 Jan 2016 14:02:20 +0000 (+0800)
Subject: crypto: algif_skcipher - Fix race condition in skcipher_check_key
X-Git-Tag: drm-fsl-dcu-for-next~1764^2~4
X-Git-Url: http://git.agner.ch/gitweb/?p=linux-drm-fsl-dcu.git;a=commitdiff_plain;h=1822793a523e5d5730b19cc21160ff1717421bc8

crypto: algif_skcipher - Fix race condition in skcipher_check_key

We need to lock the child socket in skcipher_check_key as otherwise
two simultaneous calls can cause the parent socket to be freed.

Cc: stable@vger.kernel.org
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 1f99d2d47715..dfff8b0b56df 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -755,22 +755,23 @@ static struct proto_ops algif_skcipher_ops = {
 
 static int skcipher_check_key(struct socket *sock)
 {
-	int err;
+	int err = 0;
 	struct sock *psk;
 	struct alg_sock *pask;
 	struct skcipher_tfm *tfm;
 	struct sock *sk = sock->sk;
 	struct alg_sock *ask = alg_sk(sk);
 
+	lock_sock(sk);
 	if (ask->refcnt)
-		return 0;
+		goto unlock_child;
 
 	psk = ask->parent;
 	pask = alg_sk(ask->parent);
 	tfm = pask->private;
 
 	err = -ENOKEY;
-	lock_sock(psk);
+	lock_sock_nested(psk, SINGLE_DEPTH_NESTING);
 	if (!tfm->has_key)
 		goto unlock;
 
@@ -784,6 +785,8 @@ static int skcipher_check_key(struct socket *sock)
 
 unlock:
 	release_sock(psk);
+unlock_child:
+	release_sock(sk);
 
 	return err;
 }