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: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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 @@
{
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)