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From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	David Miller <davem@davemloft.net>,
	Willem de Bruijn <willemb@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	jarno@ovn.org, Philip Pettersson <philip.pettersson@gmail.com>,
	weongyo.linux@gmail.com, netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: net/packet: use-after-free in packet_rcv_fanout
Date: Fri, 10 Feb 2017 11:16:24 -0800	[thread overview]
Message-ID: <20170210191624.GA11187@oracle.com> (raw)
In-Reply-To: <CAM_iQpWtFo80Z5yDn1Mf6bcZg+OWCyeq98WF7t+bwxGOuSjXpA@mail.gmail.com>

On (02/10/17 10:00), Cong Wang wrote:
> My understanding about the race here is packet_release() doesn't
> wait for flying packets correctly, which leads to a flying packet still
> refers to the struct sock which is being released.
> 
> This could happen because struct packet_fanout is refcn'ted, it is
   :
> At least I believe this explains the crash Dmitry reported.

hmm, the proof of the pudding is in the eating- would be good to 
be able to reliably reproduce this somewhere (thus proving that
root-cause analysis is rock-solid), maybe by introducing artificial
delays to slow down paths..

I'm travelling at the moment but may be able to give this (try
to reproduce it reliably) next week.

--Sowmini

      reply	other threads:[~2017-02-10 19:16 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-09 13:14 net/packet: use-after-free in packet_rcv_fanout Dmitry Vyukov
2017-02-09 15:12 ` Sowmini Varadhan
2017-02-09 15:17   ` Eric Dumazet
2017-02-10  1:24 ` Cong Wang
2017-02-10  3:19   ` Eric Dumazet
2017-02-10  3:23     ` Eric Dumazet
2017-02-10 17:49       ` Cong Wang
2017-02-10 17:59         ` Eric Dumazet
2017-02-10 18:02           ` Cong Wang
2017-02-10 18:15             ` Eric Dumazet
2017-02-10 18:02           ` Eric Dumazet
2017-02-10 18:34             ` Cong Wang
2017-02-13  1:42             ` Sowmini Varadhan
2017-02-13 15:17               ` Dmitry Vyukov
2017-02-17 19:27                 ` Cong Wang
2017-02-10  3:33     ` Sowmini Varadhan
2017-02-10  4:18       ` Eric Dumazet
2017-02-10 18:00       ` Cong Wang
2017-02-10 19:16         ` Sowmini Varadhan [this message]

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