On 12/06/2013 12:55 AM, Stephen Hemminger wrote: > On Thu, 5 Dec 2013 16:27:37 +0100 > Jiri Pirko <jiri@xxxxxxxxxxx> wrote: > >> 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. >> > > > I think this patch is simpler/better, it restores the old logic. > > Ps. submitting patches to bugzilla is a good way to have them ignored. > >>From Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> > > Check that incoming STP packet is received on a port assigned to bridge > before processing. It is possible to receive packet on non-bridge port > because they are multicast. > > See: > https://bugzilla.kernel.org/show_bug.cgi?id=64911 > > > Regression introduced by: > commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 > Author: Hong Zhiguo <zhiguohong@xxxxxxxxxxx> > Date: Sat Sep 14 22:42:28 2013 +0800 > > bridge: fix NULL pointer deref of br_port_get_rcu > > > Reported-by: Alexander Y. Fomichev > Signed-off-by: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> > > > --- a/net/bridge/br_stp_bpdu.c 2013-06-11 09:50:21.522919061 -0700 > +++ b/net/bridge/br_stp_bpdu.c 2013-12-05 08:46:56.090463702 -0800 > @@ -153,6 +153,9 @@ void br_stp_rcv(const struct stp_proto * > if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0) > goto err; > > + if (!br_port_exists(dev)) > + goto err; > + > p = br_port_get_rcu(dev); > if (!p) > goto err; We alreay did some cleanup jobs before mark this dev is not a port of bridge (dev->priv_flags &= ~IFF_BRIDGE_PORT), such as remove the fdb related to this port(br_fdb_delete_by_port). and seems like after these cleanup jobs, before unregister this device, if new skb is received, br_handle_local_finish will call br_fdb_update to create a new fdb whose dst points to the will-be-destroied-port. I don't know if this will cause some problems. seems we should also make sure port is unavailable before we do cleanup.
