From: David Miller <davem@davemloft.net>
To: sd@queasysnail.net
Cc: netdev@vger.kernel.org, g.nault@alphalink.fr,
lucien.xin@gmail.com, tparkin@katalix.com
Subject: Re: [PATCH net v2] l2tp: fix race condition in l2tp_tunnel_delete
Date: Thu, 21 Sep 2017 11:53:02 -0700 (PDT) [thread overview]
Message-ID: <20170921.115302.675934534188865164.davem@davemloft.net> (raw)
In-Reply-To: <6bfc5aceda47773af4c75fe7e0e3c0d255a2342d.1505828155.git.sd@queasysnail.net>
From: Sabrina Dubroca <sd@queasysnail.net>
Date: Tue, 19 Sep 2017 15:40:40 +0200
> If we try to delete the same tunnel twice, the first delete operation
> does a lookup (l2tp_tunnel_get), finds the tunnel, calls
> l2tp_tunnel_delete, which queues it for deletion by
> l2tp_tunnel_del_work.
>
> The second delete operation also finds the tunnel and calls
> l2tp_tunnel_delete. If the workqueue has already fired and started
> running l2tp_tunnel_del_work, then l2tp_tunnel_delete will queue the
> same tunnel a second time, and try to free the socket again.
>
> Add a dead flag to prevent firing the workqueue twice. Then we can
> remove the check of queue_work's result that was meant to prevent that
> race but doesn't.
>
> Also check the flag in the tunnel lookup functions, to avoid returning a
> tunnel that is already scheduled for destruction.
Sabrina, please respond to Guillaume's feedback.
Thank you.
prev parent reply other threads:[~2017-09-21 18:53 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-09-19 13:40 [PATCH net v2] l2tp: fix race condition in l2tp_tunnel_delete Sabrina Dubroca
2017-09-19 16:43 ` Guillaume Nault
2017-09-22 16:16 ` Sabrina Dubroca
2017-09-25 12:33 ` Guillaume Nault
2017-09-26 13:59 ` Sabrina Dubroca
2017-09-21 18:53 ` David Miller [this message]
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