[PATCH 3.10 01/17] l2tp: protect tunnel->del_work by ref_count

Greg Kroah-Hartman
2015-10-23T17:45:06Z

From: Alexander Couzens <lynxis@fe80.eu>

[ Upstream commit 06a15f51cf3618e32a73871ee6a547ef7fd902b5 ]

There is a small chance that tunnel_free() is called before tunnel->del_work scheduled
resulting in a zero pointer dereference.

Signed-off-by: Alexander Couzens <lynxis@fe80.eu>
Acked-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/l2tp/l2tp_core.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)

--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1381,7 +1381,7 @@ static void l2tp_tunnel_del_work(struct
tunnel = container_of(work, struct l2tp_tunnel, del_work);
sk = l2tp_tunnel_sock_lookup(tunnel);
if (!sk)
- return;
+ goto out;

sock = sk->sk_socket;

@@ -1402,6 +1402,8 @@ static void l2tp_tunnel_del_work(struct
}

l2tp_tunnel_sock_put(sk);
+out:
+ l2tp_tunnel_dec_refcount(tunnel);
}

/* Create a socket for the tunnel, if one isn't set up by
@@ -1731,8 +1733,13 @@ EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
*/
int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
{
+ l2tp_tunnel_inc_refcount(tunnel);
l2tp_tunnel_closeall(tunnel);
- return (false == queue_work(l2tp_wq, &tunnel->del_work));
+ if (false == queue_work(l2tp_wq, &tunnel->del_work)) {
+ l2tp_tunnel_dec_refcount(tunnel);
+ return 1;
+ }
+ return 0;
}
EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);