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Date: Tue, 14 Jan 2014 15:10:50 +0400
Message-ID: <CANaxB-zSkmVy+TBCa0CyReiSgubBUmyz6iUp8bxByOr7Jb9oGw@mail.gmail.com>
Subject: Re: [PATCH] netfilter: nf_conntrack: fix RCU race in
 nf_conntrack_find_get (v3)
From: Andrey Wagin <avagin@gmail.com>
To: Andrew Vagin <avagin@parallels.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>, Florian Westphal <fw@strlen.de>,
        netfilter-devel@vger.kernel.org, netfilter@vger.kernel.org,
        coreteam@netfilter.org, netdev@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, vvs@openvz.org,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Patrick McHardy <kaber@trash.net>,
        Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>,
        "David S. Miller" <davem@davemloft.net>,
        Cyrill Gorcunov <gorcunov@openvz.org>
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Sender: linux-kernel-owner@vger.kernel.org

>
> Eh, looks like this path is incomplete too:(
>
> I think we can't set a reference counter for objects which is allocated
> from a SLAB_DESTROY_BY_RCU cache. Look at the following backtrace.
>
> cpu1                                    cpu2
> ct = ____nf_conntrack_find()
>                                         destroy_conntrack
> atomic_inc_not_zero(ct)

ct->ct_general.use is zero after destroy_conntrack(). Sorry for the noise.
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