From: Jason Wang <jasowang@redhat.com>
To: davem@davemloft.net, mst@redhat.com, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org
Cc: Jason Wang <jasowang@redhat.com>
Subject: [PATCH] tuntap: fix a possible race between queue selection and changing queues
Date: Wed, 5 Jun 2013 16:44:57 +0800 [thread overview]
Message-ID: <1370421897-30933-1-git-send-email-jasowang@redhat.com> (raw)
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@redhat.com>
Cc: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/net/tun.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index f042b03..adfcde7 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) {
--
1.7.1
next reply other threads:[~2013-06-05 8:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-05 8:44 Jason Wang [this message]
2013-06-05 10:33 ` [PATCH] tuntap: fix a possible race between queue selection and changing queues Michael S. Tsirkin
2013-06-10 21:33 ` David Miller
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