[PATCH 201/241] l2tp: fix oops in l2tp_eth_create() error path

[Herton Ronaldo Krzesinski]

3.5.7.2 -stable review patch.  If anyone has any objections, please let me know.

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

From: Tom Parkin <tparkin at katalix.com>

commit 789336360e0a2aeb9750c16ab704a02cbe035e9e upstream.

When creating an L2TPv3 Ethernet session, if register_netdev() should fail for
any reason (for example, automatic naming for "l2tpeth%d" interfaces hits the
32k-interface limit), the netdev is freed in the error path.  However, the
l2tp_eth_sess structure's dev pointer is left uncleared, and this results in
l2tp_eth_delete() then attempting to unregister the same netdev later in the
session teardown.  This results in an oops.

To avoid this, clear the session dev pointer in the error path.

Signed-off-by: Tom Parkin <tparkin at katalix.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 net/l2tp/l2tp_eth.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 94840d8..80196f3 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -285,6 +285,7 @@ static int l2tp_eth_create(struct net *net, u32 tunnel_id, u32 session_id, u32 p
 
 out_del_dev:
 	free_netdev(dev);
+	spriv->dev = NULL;
 out_del_session:
 	l2tp_session_delete(session);
 out:
-- 
1.7.9.5