From 24b95685ffcdb3dc28f64b9e8af6ea3e8360fbc5 Mon Sep 17 00:00:00 2001
From: James Chapman <jchapman@katalix.com>
Date: Wed, 4 Jun 2008 15:54:07 -0700
Subject: [PATCH] l2tp: Fix possible oops if transmitting or receiving when
 tunnel goes down

Some problems have been experienced in the field which cause an oops
in the pppol2tp driver if L2TP tunnels fail while passing data.

The pppol2tp driver uses private data that is referenced via the
sk->sk_user_data of its UDP and PPPoL2TP sockets. This patch makes
sure that the driver uses sock_hold() when it holds a reference to the
sk pointer. This affects its sendmsg(), recvmsg(), getname(),
[gs]etsockopt() and ioctl() handlers.

Tested by ISP where problem was seen. System has been up 10 days with
no oops since running this patch. Without the patch, an oops would
occur every 1-2 days.

Signed-off-by: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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