Commit c03307ea authored Aug 14, 2012 by Stephen Hemminger Committed by David S. Miller Aug 15, 2012

bridge: fix rcu dereference outside of rcu_read_lock



Alternative solution for problem found by Linux Driver Verification
project (linuxtesting.org).

As it noted in the comment before the br_handle_frame_finish
function, this function should be called under rcu_read_lock.

The problem callgraph:
br_dev_xmit -> br_nf_pre_routing_finish_bridge_slow ->
 -> br_handle_frame_finish -> br_port_get_rcu -> rcu_dereference

And in this case there is no read-lock section.

Reported-by: Denis Efremov <yefremov.denis@gmail.com>
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 7bab3ae7

net/bridge/br_device.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -31,9 +31,11 @@ netdev_tx_t br_dev_xmit(struct sk_buff skb, struct net_device dev)
		struct net_bridge_mdb_entry *mdst;
		struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats);

		rcu_read_lock();
		#ifdef CONFIG_BRIDGE_NETFILTER
		if (skb->nf_bridge && (skb->nf_bridge->mask & BRNF_BRIDGED_DNAT)) {
		br_nf_pre_routing_finish_bridge_slow(skb);
		rcu_read_unlock();
		return NETDEV_TX_OK;
		}
		#endif
		@@ -48,7 +50,6 @@ netdev_tx_t br_dev_xmit(struct sk_buff skb, struct net_device dev)
		skb_reset_mac_header(skb);
		skb_pull(skb, ETH_HLEN);

		rcu_read_lock();
		if (is_broadcast_ether_addr(dest))
		br_flood_deliver(br, skb);
		else if (is_multicast_ether_addr(dest)) {