netdev - Re: [PATCH net 1/1] sctp: Start shutdown on association restart if in SHUTDOWN-SENT state and socket is closed

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Date:   Fri, 22 May 2020 15:48:33 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     jere.leppanen@...ia.com
Cc:     linux-sctp@...r.kernel.org, netdev@...r.kernel.org,
        vyasevich@...il.com, nhorman@...driver.com,
        marcelo.leitner@...il.com, David.Laight@...lab.com
Subject: Re: [PATCH net 1/1] sctp: Start shutdown on association restart if
 in SHUTDOWN-SENT state and socket is closed

From: Jere Leppänen <jere.leppanen@...ia.com>
Date: Wed, 20 May 2020 18:15:31 +0300

> Commit bdf6fa52f01b ("sctp: handle association restarts when the
> socket is closed.") starts shutdown when an association is restarted,
> if in SHUTDOWN-PENDING state and the socket is closed. However, the
> rationale stated in that commit applies also when in SHUTDOWN-SENT
> state - we don't want to move an association to ESTABLISHED state when
> the socket has been closed, because that results in an association
> that is unreachable from user space.
> 
> The problem scenario:
> 
> 1.  Client crashes and/or restarts.
> 
> 2.  Server (using one-to-one socket) calls close(). SHUTDOWN is lost.
> 
> 3.  Client reconnects using the same addresses and ports.
> 
> 4.  Server's association is restarted. The association and the socket
>     move to ESTABLISHED state, even though the server process has
>     closed its descriptor.
> 
> Also, after step 4 when the server process exits, some resources are
> leaked in an attempt to release the underlying inet sock structure in
> ESTABLISHED state:
> 
>     IPv4: Attempt to release TCP socket in state 1 00000000377288c7
> 
> Fix by acting the same way as in SHUTDOWN-PENDING state. That is, if
> an association is restarted in SHUTDOWN-SENT state and the socket is
> closed, then start shutdown and don't move the association or the
> socket to ESTABLISHED state.
> 
> Fixes: bdf6fa52f01b ("sctp: handle association restarts when the socket is closed.")
> Signed-off-by: Jere Leppänen <jere.leppanen@...ia.com>

Applied and queued up for -stable, thanks.