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Subject[PATCH 3.2 80/87] crypto: algif_hash - Fix race condition in hash_check_key
3.2.77-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Herbert Xu <herbert@gondor.apana.org.au>

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: Ben Hutchings <ben@decadent.org.uk>
---
crypto/algif_hash.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/crypto/algif_hash.c
+++ b/crypto/algif_hash.c
@@ -253,22 +253,23 @@ 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;

@@ -282,6 +283,8 @@ static int hash_check_key(struct socket

unlock:
release_sock(psk);
+unlock_child:
+ release_sock(sk);

return err;
}
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