netdev - Re: [PATCH net] l2tp: purge socket queues in the .destruct() callback

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Date:   Tue, 28 Mar 2017 21:39:50 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     g.nault@...halink.fr
Cc:     netdev@...r.kernel.org, jchapman@...alix.com
Subject: Re: [PATCH net] l2tp: purge socket queues in the .destruct()
 callback

From: Guillaume Nault <g.nault@...halink.fr>
Date: Tue, 28 Mar 2017 15:32:41 +0200

> The Rx path may grab the socket right before pppol2tp_release(), but
> nothing guarantees that it will enqueue packets before
> skb_queue_purge(). Therefore, the socket can be destroyed without its
> queues fully purged.
> 
> Fix this by purging queues in pppol2tp_session_destruct() where we're
> guaranteed nothing is still referencing the socket.
> 
> Signed-off-by: Guillaume Nault <g.nault@...halink.fr>

As a quick guess, I'm thinking this problem might have been introduced
by:

====================
commit 9e9cb6221aa7cb04765484fe87cc2d1b92edce64
Author: Guillaume Nault <g.nault@...halink.fr>
Date:   Thu Mar 6 11:15:10 2014 +0100

    l2tp: fix userspace reception on plain L2TP sockets
====================

Please add an appropriate Fixes: tag for this patch.

Thanks.