Re: [PATCH] tuntap: fix a possible race between queue selectionand changing queues

From: David Miller
Date: Mon Jun 10 2013 - 17:33:19 EST

From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Date: Wed, 5 Jun 2013 13:33:32 +0300

> On Wed, Jun 05, 2013 at 04:44:57PM +0800, Jason Wang wrote:
>> Complier may generate codes that re-read the tun->numqueues during
>> tun_select_queue(). This may be a race if vlan->numqueues were changed in the
>> same time and can lead unexpected result (e.g. very huge value).
>> We need prevent the compiler from generating such codes by adding an
>> ACCESS_ONCE() to make sure tun->numqueues were only read once.
>> Bug were introduced by commit c8d68e6be1c3b242f1c598595830890b65cea64a
>> (tuntap: multiqueue support).
>> Reported-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
>> Cc: Michael S. Tsirkin <mst@xxxxxxxxxx>
>> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> Acked-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
> This is a theoretical problem, right?
> So no need for stable.

Applied, thanks.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at