From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gao feng Subject: Re: [patch net/stable v2] br: fix use of ->rx_handler_data in code executed on non-rx_handler path Date: Fri, 06 Dec 2013 10:26:10 +0800 Message-ID: <52A135C2.9020406@cn.fujitsu.com> References: <1386257257-25258-1-git-send-email-jiri@resnulli.us> <20131205085514.4c079747@nehalam.linuxnetplumber.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, davem@davemloft.net, jtluka@redhat.com, zhiguohong@tencent.com, bridge@lists.linux-foundation.org, edumazet@google.com, laine@redhat.com, mst@redhat.com To: Stephen Hemminger , Jiri Pirko Return-path: Received: from cn.fujitsu.com ([222.73.24.84]:43020 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756710Ab3LFCZJ (ORCPT ); Thu, 5 Dec 2013 21:25:09 -0500 In-Reply-To: <20131205085514.4c079747@nehalam.linuxnetplumber.net> Sender: netdev-owner@vger.kernel.org List-ID: On 12/06/2013 12:55 AM, Stephen Hemminger wrote: > On Thu, 5 Dec 2013 16:27:37 +0100 > Jiri Pirko 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 > > 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 > 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 > > > --- 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.