From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hong Zhiguo , Eric Dumazet , "David S. Miller" Subject: [ 024/110] bridge: fix NULL pointer deref of br_port_get_rcu Date: Fri, 11 Oct 2013 12:38:04 -0700 Message-Id: <20131011193810.333393700@linuxfoundation.org> In-Reply-To: <20131011193807.584188672@linuxfoundation.org> References: <20131011193807.584188672@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hong Zhiguo [ 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(-) --- 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)