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 <m...@redhat.com>
Cc: Michael S. Tsirkin <m...@redhat.com>
Signed-off-by: Jason Wang <jasow...@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
--
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