From: WANG Cong Date: Wed, 21 Jun 2017 21:34:58 +0000 (-0700) Subject: ipv6: avoid unregistering inet6_dev for loopback X-Git-Tag: v3.10.108~32 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=fa69abfe6a07ae3c009b30271966b871799077b6;p=thirdparty%2Fkernel%2Fstable.git ipv6: avoid unregistering inet6_dev for loopback 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 Signed-off-by: Greg Kroah-Hartman Signed-off-by: Willy Tarreau --- diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 9c4aa2e22448c..5ea5f77c0ec1b 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -2892,6 +2892,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event, { struct net_device *dev = (struct net_device *) data; struct inet6_dev *idev = __in6_dev_get(dev); + struct net *net = dev_net(dev); int run_pending = 0; int err; @@ -2988,7 +2989,7 @@ 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;