From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752241AbdIIW0e (ORCPT ); Sat, 9 Sep 2017 18:26:34 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41852 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752013AbdIIWYz (ORCPT ); Sat, 9 Sep 2017 18:24:55 -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" , "WANG Cong" , "Andrey Konovalov" , "Daniel Lezcano" , "David Ahern" Date: Sat, 09 Sep 2017 22:47:15 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 212/233] ipv6: avoid unregistering inet6_dev for loopback In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8011:400e:2:6f00:88c8:c921:d332 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 3.16.48-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: WANG Cong commit 60abc0be96e00ca71bac083215ac91ad2e575096 upstream. The per netns loopback_dev->ip6_ptr is unregistered and set to NULL when its mtu is set to smaller than IPV6_MIN_MTU, this leads to that we could set rt->rt6i_idev NULL after a rt6_uncached_list_flush_dev() and then crash after another call. In this case we should just bring its inet6_dev down, rather than unregistering it, at least prior to commit 176c39af29bc ("netns: fix addrconf_ifdown kernel panic") we always override the case for loopback. Thanks a lot to Andrey for finding a reliable reproducer. Fixes: 176c39af29bc ("netns: fix addrconf_ifdown kernel panic") Reported-by: Andrey Konovalov Cc: Andrey Konovalov Cc: Daniel Lezcano Cc: David Ahern Signed-off-by: Cong Wang Acked-by: David Ahern Tested-by: Andrey Konovalov Signed-off-by: David S. Miller [bwh: Backported to 3.16: the NETDEV_CHANGEMTU case used to fall-through to the NETDEV_DOWN case here, so replace that with a separate call to addrconf_ifdown()] Signed-off-by: Ben Hutchings --- --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2823,6 +2823,7 @@ static int addrconf_notify(struct notifi { struct net_device *dev = netdev_notifier_info_to_dev(ptr); struct inet6_dev *idev = __in6_dev_get(dev); + struct net *net = dev_net(dev); int run_pending = 0; int err; @@ -2916,7 +2917,7 @@ static int addrconf_notify(struct notifi * IPV6_MIN_MTU stop IPv6 on this interface. */ if (dev->mtu < IPV6_MIN_MTU) - addrconf_ifdown(dev, 1); + addrconf_ifdown(dev, dev != net->loopback_dev); } break; @@ -2937,6 +2938,8 @@ static int addrconf_notify(struct notifi * if MTU under IPV6_MIN_MTU. * Stop IPv6 on this interface. */ + addrconf_ifdown(dev, dev != net->loopback_dev); + break; case NETDEV_DOWN: case NETDEV_UNREGISTER: