From: WANG Cong Date: Wed, 21 Jun 2017 21:34:58 +0000 (-0700) Subject: ipv6: avoid unregistering inet6_dev for loopback X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=60abc0be96e00ca71bac083215ac91ad2e575096;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git ipv6: avoid unregistering inet6_dev for loopback 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 --- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 686c92375e81..1d2dbace42ff 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -3369,6 +3369,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, struct net_device *dev = netdev_notifier_info_to_dev(ptr); struct netdev_notifier_changeupper_info *info; struct inet6_dev *idev = __in6_dev_get(dev); + struct net *net = dev_net(dev); int run_pending = 0; int err; @@ -3384,7 +3385,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, case NETDEV_CHANGEMTU: /* if MTU under 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; } @@ -3500,7 +3501,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, * 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;