Re: net/packet: use-after-free in packet_rcv_fanout

From	Sowmini Varadhan <sowmini.varadhan@oracle.com>
Newsgroups	linux.kernel
Subject	Re: net/packet: use-after-free in packet_rcv_fanout
Date	2017-02-10 20:20 +0100
Message-ID	<t9oTD-7BA-3@gated-at.bofh.it> (permalink)
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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

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net/packet: use-after-free in packet_rcv_fanout Dmitry Vyukov <dvyukov@google.com> - 2017-02-09 14:20 +0100
  Re: net/packet: use-after-free in packet_rcv_fanout Sowmini Varadhan <sowmini.varadhan@oracle.com> - 2017-02-09 16:20 +0100
    Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <edumazet@google.com> - 2017-02-09 16:20 +0100
  Re: net/packet: use-after-free in packet_rcv_fanout Cong Wang <xiyou.wangcong@gmail.com> - 2017-02-10 02:30 +0100
    Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <eric.dumazet@gmail.com> - 2017-02-10 04:20 +0100
      Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <eric.dumazet@gmail.com> - 2017-02-10 04:30 +0100
        Re: net/packet: use-after-free in packet_rcv_fanout Cong Wang <xiyou.wangcong@gmail.com> - 2017-02-10 19:00 +0100
          Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <eric.dumazet@gmail.com> - 2017-02-10 19:10 +0100
            Re: net/packet: use-after-free in packet_rcv_fanout Cong Wang <xiyou.wangcong@gmail.com> - 2017-02-10 19:20 +0100
              Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <eric.dumazet@gmail.com> - 2017-02-10 19:30 +0100
            Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <eric.dumazet@gmail.com> - 2017-02-10 19:20 +0100
              Re: net/packet: use-after-free in packet_rcv_fanout Cong Wang <xiyou.wangcong@gmail.com> - 2017-02-10 19:50 +0100
      Re: net/packet: use-after-free in packet_rcv_fanout Sowmini Varadhan <sowmini.varadhan@oracle.com> - 2017-02-10 04:40 +0100
        Re: net/packet: use-after-free in packet_rcv_fanout Eric Dumazet <edumazet@google.com> - 2017-02-10 05:30 +0100
        Re: net/packet: use-after-free in packet_rcv_fanout Cong Wang <xiyou.wangcong@gmail.com> - 2017-02-10 19:10 +0100
          Re: net/packet: use-after-free in packet_rcv_fanout Sowmini Varadhan <sowmini.varadhan@oracle.com> - 2017-02-10 20:20 +0100

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