From 960b8e5018a552f62cfbc0dfe94be7b6ba178f13 Mon Sep 17 00:00:00 2001 From: Hong Zhiguo Date: Sat, 14 Sep 2013 22:42:28 +0800 Subject: [PATCH] bridge: fix NULL pointer deref of br_port_get_rcu [ Upstream commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 ] The NULL deref happens when br_handle_frame is called between these 2 lines of del_nbp: dev->priv_flags &= ~IFF_BRIDGE_PORT; /* --> br_handle_frame is called at this time */ netdev_rx_handler_unregister(dev); In br_handle_frame the return of br_port_get_rcu(dev) is dereferenced without check but br_port_get_rcu(dev) returns NULL if: !(dev->priv_flags & IFF_BRIDGE_PORT) Eric Dumazet pointed out the testing of IFF_BRIDGE_PORT is not necessary here since we're in rcu_read_lock and we have synchronize_net() in netdev_rx_handler_unregister. So remove the testing of IFF_BRIDGE_PORT and by the previous patch, make sure br_port_get_rcu is called in bridging code. Signed-off-by: Hong Zhiguo Acked-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/bridge/br_private.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h index 84e081060b66..e696833a31b5 100644 --- a/net/bridge/br_private.h +++ b/net/bridge/br_private.h @@ -183,10 +183,7 @@ struct net_bridge_port static inline struct net_bridge_port *br_port_get_rcu(const struct net_device *dev) { - struct net_bridge_port *port = - rcu_dereference_rtnl(dev->rx_handler_data); - - return br_port_exists(dev) ? port : NULL; + return rcu_dereference(dev->rx_handler_data); } static inline struct net_bridge_port *br_port_get_rtnl(const struct net_device *dev) -- 2.34.1