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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D174AC1DA@AcuExch.aculab.com>
Date: Mon, 6 Oct 2014 11:09:52 +0000
From: David Laight <David.Laight@...LAB.COM>
To: 'David Miller' <davem@...emloft.net>,
"vyasevich@...il.com" <vyasevich@...il.com>
CC: "netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: RE: [PATCH] sctp: handle association restarts when the socket is
closed.
From: David Miller
> From: Vladislav Yasevich <vyasevich@...il.com>
> Date: Fri, 3 Oct 2014 18:16:20 -0400
>
> > From: Vlad Yasevich <vyasevich@...il.com>
> >
> > Currently association restarts do not take into consideration the
> > state of the socket. When a restart happens, the current assocation
> > simply transitions into established state. This creates a condition
> > where a remote system, through a the restart procedure, may create a
> > local association that is no way reachable by user. The conditions
> > to trigger this are as follows:
> > 1) Remote does not acknoledge some data causing data to remain
> > outstanding.
> > 2) Local application calls close() on the socket. Since data
> > is still outstanding, the association is placed in SHUTDOWN_PENDING
> > state. However, the socket is closed.
> > 3) The remote tries to create a new association, triggering a restart
> > on the local system. The association moves from SHUTDOWN_PENDING
> > to ESTABLISHED. At this point, it is no longer reachable by
> > any socket on the local system.
> >
> > This patch addresses the above situation by moving the newly ESTABLISHED
> > association into SHUTDOWN-SENT state and bundling a SHUTDOWN after
> > the COOKIE-ACK chunk. This way, the restarted associate immidiately
> > enters the shutdown procedure and forces the termination of the
> > unreachable association.
> >
> > Reported-by: David Laight <David.Laight@...lab.com>
> > Signed-off-by: Vlad Yasevich <vyasevich@...il.com>
>
> Applied, thanks.
>
> Candidate for -stable?
Maybe, but while I raised the problem and tested the fix, I added
a workaround to our M3UA code to ABORT sctp connections.
I'll predicate it on a kernel version when I know which one it is in,
but I'm not going to check backports to old distributions.
(I'm tempted to disable sctp on 2.6.18 kernels...)
So I'm not worried -stable.
Other sctp users may be more worried.
David
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