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 176c39af29
("netns: fix addrconf_ifdown kernel panic") we always
override the case for loopback.

Thanks a lot to Andrey for finding a reliable reproducer.

Fixes: 176c39af29 ("netns: fix addrconf_ifdown kernel panic")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Daniel Lezcano <dlezcano@fr.ibm.com>
Cc: David Ahern <dsahern@gmail.com>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Acked-by: David Ahern <dsahern@gmail.com>
Tested-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.2: 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 <ben@decadent.org.uk>

This commit is contained in:

WANG Cong

2017-06-21 14:34:58 -07:00

committed by

syphyr

parent cb4e7ced75

commit 7abc0b32da

1 changed files with 2 additions and 0 deletions

									
										2

net/ipv6/addrconf.c

										View File
									
				@ -3087,6 +3087,8 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,

						 * MTU falled under IPV6_MIN_MTU.

						 * Stop IPv6 on this interface.

						 */

						addrconf_ifdown(dev, dev != net->loopback_dev);

						break;

					case NETDEV_DOWN:

					case NETDEV_UNREGISTER:

ipv6: avoid unregistering inet6_dev for loopback

2 net/ipv6/addrconf.c Unescape Escape View File

2

net/ipv6/addrconf.c

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