ipv6: avoid unregistering inet6_dev for loopback
authorWANG Cong <xiyou.wangcong@gmail.com>
Wed, 21 Jun 2017 21:34:58 +0000 (14:34 -0700)
committerDavid S. Miller <davem@davemloft.net>
Thu, 22 Jun 2017 17:21:44 +0000 (13:21 -0400)
commit60abc0be96e00ca71bac083215ac91ad2e575096
treefe2faac629a89738ba334d92eab198b800101e99
parent8c4354ef590ec8b3b10eb7f29d8c8ae56709b96b
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 <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>
net/ipv6/addrconf.c