From: Jason Wang Date: Wed, 5 Jun 2013 08:44:57 +0000 (+0800) Subject: tuntap: fix a possible race between queue selection and changing queues X-Git-Tag: accepted/tizen/common/20141203.182822~2082^2~13 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=92bb73ea2c434618a68a58a2f3a5c3fd0b660d18;p=platform%2Fkernel%2Flinux-arm64.git tuntap: fix a possible race between queue selection and changing queues 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 Cc: Michael S. Tsirkin Signed-off-by: Jason Wang Acked-by: Michael S. Tsirkin Signed-off-by: David S. Miller --- diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 89776c5..b1cbfbc 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -352,7 +352,7 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb) u32 numqueues = 0; rcu_read_lock(); - numqueues = tun->numqueues; + numqueues = ACCESS_ONCE(tun->numqueues); txq = skb_get_rxhash(skb); if (txq) {