From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 26 Feb 2016 11:44:11 +0000 (+0100)
Subject: Backport fix for crypto: algif_skcipher - Fix race condition in skcipher_check_key
X-Git-Tag: v4.1.12-92~150^2~221
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=1a1790e2866126b855fb7e7be19636780795693a;p=users%2Fjedix%2Flinux-maple.git

Backport fix for crypto: algif_skcipher - Fix race condition in skcipher_check_key

Orabug: stable_rc4

commit 1822793a523e5d5730b19cc21160ff1717421bc8 upstream.

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>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 64c4131f16acba869e5280ee46e7dbf93fd8b960)

Signed-off-by: Dan Duval <dan.duval@oracle.com>
---

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 83bcf75b358e0..c0f03562a1457 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -757,22 +757,23 @@ 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;
 
@@ -786,6 +787,8 @@ static int skcipher_check_key(struct socket *sock)
 
 unlock:
 	release_sock(psk);
+unlock_child:
+	release_sock(sk);
 
 	return err;
 }