linux-kernel - [ 74/82] l2tp: fix oops in l2tp_eth

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Message-Id: <20121114053944.039777768@decadent.org.uk>
Date:	Wed, 14 Nov 2012 05:40:47 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Tom Parkin <tparkin@...alix.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 74/82] l2tp: fix oops in l2tp_eth_create() error path

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

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

From: Tom Parkin <tparkin@...alix.com>

[ Upstream commit 789336360e0a2aeb9750c16ab704a02cbe035e9e ]

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@...alix.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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 2cef50b..64164fb 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -269,6 +269,7 @@ 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:


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