Messages in this thread | | | Date | Wed, 5 Jun 2013 13:35:28 +0300 | From | "Michael S. Tsirkin" <> | Subject | Re: [net-next rfc V3 1/9] macvtap: fix a possible race between queue selection and changing queues |
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On Wed, Jun 05, 2013 at 02:36:24PM +0800, Jason Wang wrote: > Complier may generate codes that re-read the vlan->numvtaps during > macvtap_get_queue(). This may lead a race if vlan->numvtaps were changed in the > same time and which 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 vlan->numvtaps were only read once. > > Signed-off-by: Jason Wang <jasowang@redhat.com>
I would add that this is a theoretical issue, so no need for stable.
Acked-by: Michael S. Tsirkin <mst@redhat.com>
> --- > drivers/net/macvtap.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c > index 68efb91..5e485e3 100644 > --- a/drivers/net/macvtap.c > +++ b/drivers/net/macvtap.c > @@ -172,7 +172,7 @@ static struct macvtap_queue *macvtap_get_queue(struct net_device *dev, > { > struct macvlan_dev *vlan = netdev_priv(dev); > struct macvtap_queue *tap = NULL; > - int numvtaps = vlan->numvtaps; > + int numvtaps = ACCESS_ONCE(vlan->numvtaps); > __u32 rxq; > > if (!numvtaps) > -- > 1.7.1
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