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Date: Fri, 11 Oct 2013 12:38:26 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Hong Zhiguo <zhiguohong@...cent.com>, Eric Dumazet <edumazet@...gle.com>, "David S. Miller" <davem@...emloft.net> Subject: [ 025/135] bridge: fix NULL pointer deref of br_port_get_rcu 3.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hong Zhiguo <zhiguohong@...cent.com> [ 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 <zhiguohong@...cent.com> Acked-by: Eric Dumazet <edumazet@...gle.com> Signed-off-by: David S. Miller <davem@...emloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- 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 @@ -202,10 +202,7 @@ 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) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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