Re: [Patch net] ipv6: initialize route null entry in addrconf_init()

On 5/4/17 10:51 AM, David Miller wrote:

From: Andrey Konovalov <redacted>
Date: Thu, 4 May 2017 14:28:37 +0200

quoted

On Thu, May 4, 2017 at 7:07 AM, Cong Wang [off-list ref] wrote:

quoted

Andrey reported a crash on init_net.ipv6.ip6_null_entry->rt6i_idev
since it is always NULL.

This is clearly wrong, we have code to initialize it to loopback_dev,
unfortunately the order is still not correct.

loopback_dev is registered very early during boot, we lose a chance
to re-initialize it in notifier. addrconf_init() is called after
ip6_route_init(), which means we have no chance to correct it.

Fix it by moving this initialization explicitly after
ipv6_add_dev(init_net.loopback_dev) in addrconf_init().

Reported-by: Andrey Konovalov <redacted>
Signed-off-by: Cong Wang <redacted>

Hi Cong,

This fixes the bug triggered by my reproducer.

Thanks!

Tested-by: Andrey Konovalov <redacted>

Applied and queued up for -stable, thanks.

This is not the complete solution; it only fixes init_net. It still
blows up when you do:

unshare -n
./rt6_device_match


same exact stack trace