bridge: fix RCU races with bridge port

The macro br_port_exists() is not enough protection when only
RCU is being used. There is a tiny race where other CPU has cleared port
handler hook, but is bridge port flag might still be set.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 4 deletions

diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
index 89ad25a76202..427f90a8ab7b 100644
--- a/net/bridge/br_if.c
+++ b/net/bridge/br_if.c
@@ -475,11 +475,8 @@ int br_del_if(struct net_bridge *br, struct net_device *dev)
 {
         struct net_bridge_port *p;
 
-        if (!br_port_exists(dev))
-                return -EINVAL;
-
         p = br_port_get(dev);
-        if (p->br != br)
+        if (!p || p->br != br)
                 return -EINVAL;
 
         del_nbp(p);