net: bridge: Fix locking in br_fdb_find_port()

Callers of br_fdb_find() need to hold the hash lock, which br_fdb_find_port() doesn't do. However, since br_fdb_find_port() is not doing any actual FDB manipulation, the hash lock is not really needed at all. So convert to br_fdb_find_rcu(), surrounded by rcu_read_lock() / _unlock() pair. The device pointer copied from inside the FDB entry is then kept alive by the RTNL lock, which br_fdb_find_port() asserts. Fixes: 4d4fd36 ("net: bridge: Publish bridge accessor functions") Signed-off-by: Petr Machata <[email protected]> Acked-by: Nikolay Aleksandrov <[email protected]> Signed-off-by: David S. Miller <[email protected]>
paulburton · Jun 8, 2018 · 873aca2 · 873aca2
1 parent 6c206b2
commit 873aca2
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/net/bridge/br_fdb.c b/net/bridge/br_fdb.c
@@ -135,9 +135,11 @@ struct net_device *br_fdb_find_port(const struct net_device *br_dev,
 		return NULL;
 
 	br = netdev_priv(br_dev);
-	f = br_fdb_find(br, addr, vid);
+	rcu_read_lock();
+	f = br_fdb_find_rcu(br, addr, vid);
 	if (f && f->dst)
 		dev = f->dst->dev;
+	rcu_read_unlock();
 
 	return dev;
 }