From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Fri, 26 Feb 2016 11:44:11 +0000 (+0100)
Subject: crypto: algif_skcipher - Fix race condition in skcipher_check_key
X-Git-Tag: v3.18.31~1
X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7855e916590ab8d97abcba3d0dc735bcfa55561d;p=linux

crypto: algif_skcipher - Fix race condition in skcipher_check_key

    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>
---

diff --git a/crypto/algif_skcipher.c b/crypto/algif_skcipher.c
index 9cf9aa5df432..d2cacc7f079f 100644
--- a/crypto/algif_skcipher.c
+++ b/crypto/algif_skcipher.c
@@ -551,22 +551,23 @@ 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;
 
@@ -580,6 +581,8 @@ static int skcipher_check_key(struct socket *sock)
 
 unlock:
 	release_sock(psk);
+unlock_child:
+	release_sock(sk);
 
 	return err;
 }