crypto: algif_hash - Fix race condition in hash_check_key

commit ad46d7e33219218605ea619e32553daf4f346b9f upstream.

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

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 3653ab60ec7981f134e925b229dbcece95ccd009..608a7562839d2fe549fbebd8714733436ed2c481 100644 (file)
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -242,22 +242,23 @@ 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;
 
@@ -271,6 +272,8 @@ static int hash_check_key(struct socket *sock)
 
 unlock:
        release_sock(psk);
+unlock_child:
+       release_sock(sk);
 
        return err;
 }