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From: Xin Long <lucien.xin@gmail.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-sctp@vger.kernel.org, netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Kostya Serebryany <kcc@google.com>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: net/sctp: list double add warning in sctp_endpoint_add_asoc
Date: Wed, 5 Apr 2017 01:29:19 +0800	[thread overview]
Message-ID: <CADvbK_f1FEGRnucuMkQT6RKm0G1tKcfHyj=-GqxgzQ4iQoBLCg@mail.gmail.com> (raw)
In-Reply-To: <CAAeHK+zwbeT=jBRRSf2KYXWM=eUZAEe5QHvKPYGG5qWh6A0JGQ@mail.gmail.com>

On Tue, Apr 4, 2017 at 9:28 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
> Hi,
>
> I've got the following error report while fuzzing the kernel with syzkaller.
>
> On commit a71c9a1c779f2499fb2afc0553e543f18aff6edf (4.11-rc5).
>
> A reproducer and .config are attached.
The script is pretty hard to reproduce the issue in my env.
But there seems a case to cause a use-after-free when out of snd_buf.

the case is like:
-----------
one thread:                       another thread:
                                  sctp_rcv hold asoc (hold transport)
                                  enqueue the chunk to backlog queue
                                  [refcnt=2]

sctp_close free assoc
[refcnt=1]

sctp_sendmsg find asoc
but not hold it

out of snd_buf
hold asoc, schedule out
[refcnt = 2]

                                  process backlog and put asoc/transport
                                  [refcnt=1]

schedule in, put asoc
[refcnt=0] <--- destroyed

sctp_sendmsg continue
using asoc, panic

--------------------

Maybe we should check if asoc is dead already when schedule back
into sctp_sendmsg because of out of snd_buf.

WARNING: multiple messages have this Message-ID

From: Xin Long <lucien.xin@gmail.com>
To: Andrey Konovalov <andreyknvl@google.com>
Cc: Vlad Yasevich <vyasevich@gmail.com>,
	Neil Horman <nhorman@tuxdriver.com>,
	"David S. Miller" <davem@davemloft.net>,
	linux-sctp@vger.kernel.org, netdev <netdev@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Kostya Serebryany <kcc@google.com>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: net/sctp: list double add warning in sctp_endpoint_add_asoc
Date: Tue, 04 Apr 2017 17:29:19 +0000	[thread overview]
Message-ID: <CADvbK_f1FEGRnucuMkQT6RKm0G1tKcfHyj=-GqxgzQ4iQoBLCg@mail.gmail.com> (raw)
In-Reply-To: <CAAeHK+zwbeT=jBRRSf2KYXWM=eUZAEe5QHvKPYGG5qWh6A0JGQ@mail.gmail.com>

On Tue, Apr 4, 2017 at 9:28 PM, Andrey Konovalov <andreyknvl@google.com> wrote:
> Hi,
>
> I've got the following error report while fuzzing the kernel with syzkaller.
>
> On commit a71c9a1c779f2499fb2afc0553e543f18aff6edf (4.11-rc5).
>
> A reproducer and .config are attached.
The script is pretty hard to reproduce the issue in my env.
But there seems a case to cause a use-after-free when out of snd_buf.

the case is like:
-----------
one thread:                       another thread:
                                  sctp_rcv hold asoc (hold transport)
                                  enqueue the chunk to backlog queue
                                  [refcnt=2]

sctp_close free assoc
[refcnt=1]

sctp_sendmsg find asoc
but not hold it

out of snd_buf
hold asoc, schedule out
[refcnt = 2]

                                  process backlog and put asoc/transport
                                  [refcnt=1]

schedule in, put asoc
[refcnt=0] <--- destroyed

sctp_sendmsg continue
using asoc, panic

--------------------

Maybe we should check if asoc is dead already when schedule back
into sctp_sendmsg because of out of snd_buf.

  reply	other threads:[~2017-04-04 17:29 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-04 13:28 Andrey Konovalov
2017-04-04 17:29 ` Xin Long [this message]
2017-04-04 17:29   ` Xin Long
2017-04-04 21:14   ` Marcelo Ricardo Leitner
2017-04-04 21:14     ` Marcelo Ricardo Leitner
2017-04-05 10:48     ` Xin Long
2017-04-05 10:48       ` Xin Long
2017-04-05 12:44       ` Marcelo Ricardo Leitner
2017-04-05 12:44         ` Marcelo Ricardo Leitner
2017-04-05 14:03         ` Andrey Konovalov
2017-04-05 14:03           ` Andrey Konovalov
2017-04-05 14:02     ` Andrey Konovalov
2017-04-05 14:02       ` Andrey Konovalov
2017-04-05 14:22       ` Marcelo Ricardo Leitner
2017-04-05 14:22         ` Marcelo Ricardo Leitner

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