From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller 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 15:43:21 -0500 (EST) Message-ID: <20131206.154321.1673089712073824539.davem@davemloft.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: 7bit Cc: netdev@vger.kernel.org, jtluka@redhat.com, zhiguohong@tencent.com, bridge@lists.linux-foundation.org, stephen@networkplumber.org, edumazet@google.com, laine@redhat.com, mst@redhat.com To: jiri@resnulli.us Return-path: Received: from shards.monkeyblade.net ([149.20.54.216]:42365 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751030Ab3LFUnX (ORCPT ); Fri, 6 Dec 2013 15:43:23 -0500 In-Reply-To: <1386257257-25258-1-git-send-email-jiri@resnulli.us> Sender: netdev-owner@vger.kernel.org List-ID: From: Jiri Pirko 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 > Debugged-by: Michael S. Tsirkin > Signed-off-by: Michael S. Tsirkin > Signed-off-by: Jiri Pirko > --- > v1->v2: moved br_port_get_check_rcu definition below br_handle_frame definition Applied and queued up for -stable, thanks Jiri.