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Message-ID: <1485877498.6360.115.camel@edumazet-glaptop3.roam.corp.google.com>
Subject: Re: net: suspicious RCU usage in nf_hook
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>, David Miller <davem@davemloft.net>,
        Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>,
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        Pablo Neira Ayuso <pablo@netfilter.org>,
        netfilter-devel@vger.kernel.org,
        syzkaller <syzkaller@googlegroups.com>
Date: Tue, 31 Jan 2017 07:44:58 -0800
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On Mon, 2017-01-30 at 22:19 -0800, Cong Wang wrote:

> 
> The context is process context (TX path before hitting qdisc), and
> BH is not disabled, so in_interrupt() doesn't catch it. Hmm, this
> makes me thinking maybe we really need to disable BH in this
> case for nf_hook()? But it is called in RX path too, and BH is
> already disabled there.

ipt_do_table() and similar netfilter entry points disable BH.

Maybe it is done too late.