crypto: algif_hash - Fix race condition in hash_check_key

[ Upstream commit ad46d7e33219218605ea619e32553daf4f346b9f ]

We need to lock the child socket in hash_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_hash.c b/crypto/algif_hash.c
index 1867020..7b5018b 100644 (file)
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -234,22 +234,23 @@ static struct proto_ops algif_hash_ops = {
 
 static int hash_check_key(struct socket *sock)
 {
-       int err;
+       int err = 0;
        struct sock *psk;
        struct alg_sock *pask;
        struct algif_hash_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;
 
@@ -263,6 +264,8 @@ static int hash_check_key(struct socket *sock)
 
 unlock:
        release_sock(psk);
+unlock_child:
+       release_sock(sk);
 
        return err;
 }