From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752805AbbHBAK6 (ORCPT ); Sat, 1 Aug 2015 20:10:58 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35964 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbbHBAJs (ORCPT ); Sat, 1 Aug 2015 20:09:48 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "David S. Miller" , "Herbert Xu" , "Nikolay Aleksandrov" Date: Sun, 02 Aug 2015 01:02:37 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 122/164] bridge: fix multicast router rlist endless loop In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.70-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Nikolay Aleksandrov commit 1a040eaca1a22f8da8285ceda6b5e4a2cb704867 upstream. Since the addition of sysfs multicast router support if one set multicast_router to "2" more than once, then the port would be added to the hlist every time and could end up linking to itself and thus causing an endless loop for rlist walkers. So to reproduce just do: echo 2 > multicast_router; echo 2 > multicast_router; in a bridge port and let some igmp traffic flow, for me it hangs up in br_multicast_flood(). Fix this by adding a check in br_multicast_add_router() if the port is already linked. The reason this didn't happen before the addition of multicast_router sysfs entries is because there's a !hlist_unhashed check that prevents it. Signed-off-by: Nikolay Aleksandrov Fixes: 0909e11758bd ("bridge: Add multicast_router sysfs entries") Acked-by: Herbert Xu Signed-off-by: David S. Miller [bwh: Backported to 3.2: adjust context] Signed-off-by: Ben Hutchings --- net/bridge/br_multicast.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/net/bridge/br_multicast.c +++ b/net/bridge/br_multicast.c @@ -991,6 +991,9 @@ static void br_multicast_add_router(stru struct net_bridge_port *p; struct hlist_node *n, *slot = NULL; + if (!hlist_unhashed(&port->rlist)) + return; + hlist_for_each_entry(p, n, &br->router_list, rlist) { if ((unsigned long) port >= (unsigned long) p) break; @@ -1018,12 +1021,8 @@ static void br_multicast_mark_router(str if (port->multicast_router != 1) return; - if (!hlist_unhashed(&port->rlist)) - goto timer; - br_multicast_add_router(br, port); -timer: mod_timer(&port->multicast_router_timer, now + br->multicast_querier_interval); }