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>
diff --git a/net/bridge/br_netlink.c b/net/bridge/br_netlink.c
index 4a6a378..e3de0a4 100644
--- a/net/bridge/br_netlink.c
+++ b/net/bridge/br_netlink.c
@@ -119,11 +119,13 @@
idx = 0;
for_each_netdev(net, dev) {
+ struct net_bridge_port *port = br_port_get(dev);
+
/* not a bridge port */
- if (!br_port_exists(dev) || idx < cb->args[0])
+ if (!port || idx < cb->args[0])
goto skip;
- if (br_fill_ifinfo(skb, br_port_get(dev),
+ if (br_fill_ifinfo(skb, port,
NETLINK_CB(cb->skb).pid,
cb->nlh->nlmsg_seq, RTM_NEWLINK,
NLM_F_MULTI) < 0)
@@ -169,9 +171,9 @@
if (!dev)
return -ENODEV;
- if (!br_port_exists(dev))
- return -EINVAL;
p = br_port_get(dev);
+ if (!p)
+ return -EINVAL;
/* if kernel STP is running, don't allow changes */
if (p->br->stp_enabled == BR_KERNEL_STP)