From: Pablo Neira Ayuso <pablo@netfilter.org>
Date: Thu, 5 Jul 2012 13:42:10 +0000 (+0200)
Subject: netfilter: nf_ct_ecache: fix crash with multiple containers, one shutting down
X-Git-Tag: v3.5~24^2~25^2
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6bd0405bb4196b44f1acb7a58f11382cdaf6f7f0;p=pandora-kernel.git

netfilter: nf_ct_ecache: fix crash with multiple containers, one shutting down

Hans reports that he's still hitting:

BUG: unable to handle kernel NULL pointer dereference at 000000000000027c
IP: [<ffffffff813615db>] netlink_has_listeners+0xb/0x60
PGD 0
Oops: 0000 [#3] PREEMPT SMP
CPU 0

It happens when adding a number of containers with do:

nfct_query(h, NFCT_Q_CREATE, ct);

and most likely one namespace shuts down.

this problem was supposed to be fixed by:
70e9942 netfilter: nf_conntrack: make event callback registration per-netns

Still, it was missing one rcu_access_pointer to check if the callback
is set or not.

Reported-by: Hans Schillstrom <hans@schillstrom.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
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