[stable,3.10.y,13/18] crypto: algif_hash - Fix race condition in hash_check_key

Commit Message

Andrey Ryabinin Oct. 27, 2016, 2:29 p.m. UTC

From: Herbert Xu <[e-mail]>

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.

Cc: [e-mail]
Signed-off-by: Herbert Xu <[e-mail]>
Signed-off-by: Andrey Ryabinin <[e-mail]>
---
 crypto/algif_hash.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

Patch

diff --git a/crypto/algif_hash.c b/crypto/algif_hash.c
index 512aa36..d11d431 100644
--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -255,22 +255,23 @@  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;
 
@@ -284,6 +285,8 @@  static int hash_check_key(struct socket *sock)
 
 unlock:
 	release_sock(psk);
+unlock_child:
+	release_sock(sk);
 
 	return err;
 }