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Commit ed0483fa authored by Jason Wang's avatar Jason Wang Committed by David S. Miller
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macvtap: fix a possible race between queue selection and changing queues 



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.

Acked-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e403d295

drivers/net/macvtap.c

+1 −1
Original line number Diff line number Diff line
@@ -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)