From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: [patch net/stable v2] br: fix use of ->rx_handler_data in code executed on non-rx_handler path Date: Thu, 5 Dec 2013 08:55:14 -0800 Message-ID: <20131205085514.4c079747@nehalam.linuxnetplumber.net> References: <1386257257-25258-1-git-send-email-jiri@resnulli.us> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT 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: Jiri Pirko Return-path: Received: from mail-pd0-f182.google.com ([209.85.192.182]:41619 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756857Ab3LEQzT convert rfc822-to-8bit (ORCPT ); Thu, 5 Dec 2013 11:55:19 -0500 Received: by mail-pd0-f182.google.com with SMTP id v10so25149158pde.27 for ; Thu, 05 Dec 2013 08:55:19 -0800 (PST) In-Reply-To: <1386257257-25258-1-git-send-email-jiri@resnulli.us> Sender: netdev-owner@vger.kernel.org List-ID: 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;