From: Jiri Pirko <jiri@xxxxxxxxxxx> Date: Thu, 5 Dec 2013 16:27:37 +0100 > br_stp_rcv() is reached by non-rx_handler path. That means there is no > guarantee that dev is bridge port and therefore simple NULL check of > ->rx_handler_data is not enough. There is need to check if dev is really > bridge port and since only rcu read lock is held here, do it by checking > ->rx_handler pointer. > > Note that synchronize_net() in netdev_rx_handler_unregister() ensures > this approach as valid. > > Introduced originally by: > commit f350a0a87374418635689471606454abc7beaa3a > "bridge: use rx_handler_data pointer to store net_bridge_port pointer" > > Fixed but not in the best way by: > commit b5ed54e94d324f17c97852296d61a143f01b227a > "bridge: fix RCU races with bridge port" > > Reintroduced by: > commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 > "bridge: fix NULL pointer deref of br_port_get_rcu" > > Please apply to stable trees as well. Thanks. > > RH bugzilla reference: https://bugzilla.redhat.com/show_bug.cgi?id=1025770 > > Reported-by: Laine Stump <laine@xxxxxxxxxx> > Debugged-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> > Signed-off-by: Jiri Pirko <jiri@xxxxxxxxxxx> > --- > v1->v2: moved br_port_get_check_rcu definition below br_handle_frame definition Applied and queued up for -stable, thanks Jiri.
