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/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
index a1dcf83..cbc9f39 100644
--- a/net/bridge/netfilter/ebtables.c
+++ b/net/bridge/netfilter/ebtables.c
@@ -128,6 +128,7 @@
const struct net_device *in, const struct net_device *out)
{
const struct ethhdr *h = eth_hdr(skb);
+ const struct net_bridge_port *p;
__be16 ethproto;
int verdict, i;
@@ -148,13 +149,11 @@
if (FWINV2(ebt_dev_check(e->out, out), EBT_IOUT))
return 1;
/* rcu_read_lock()ed by nf_hook_slow */
- if (in && br_port_exists(in) &&
- FWINV2(ebt_dev_check(e->logical_in, br_port_get_rcu(in)->br->dev),
- EBT_ILOGICALIN))
+ if (in && (p = br_port_get_rcu(in)) != NULL &&
+ FWINV2(ebt_dev_check(e->logical_in, p->br->dev), EBT_ILOGICALIN))
return 1;
- if (out && br_port_exists(out) &&
- FWINV2(ebt_dev_check(e->logical_out, br_port_get_rcu(out)->br->dev),
- EBT_ILOGICALOUT))
+ if (out && (p = br_port_get_rcu(out)) != NULL &&
+ FWINV2(ebt_dev_check(e->logical_out, p->br->dev), EBT_ILOGICALOUT))
return 1;
if (e->bitmask & EBT_SOURCEMAC) {