On 16/12/17 12:40, Nikolay Aleksandrov wrote:
> On 16/12/17 11:29, Nikolay Aleksandrov wrote:
>> On 16/12/17 11:17, Nikolay Aleksandrov wrote:
>>> On 16/12/17 02:37, Andrei Vagin wrote:
>>>> Hi,
>>>>
>>>> We run criu tests for linux-next and today we get this bug:
>>>>
>>>> The kernel version is 4.15.0-rc3-next-20171215
>>>>
>>>> [ 235.397328] BUG: unable to handle kernel NULL pointer dereference
>>>> at 000000000000000c
>>>> [ 235.398624] IP: fdb_find_rcu+0x3c/0x130
>>> [snip]
>>>
>>> Hi,
>>> Thanks for the report, I've missed the changelink before dev creation case
>>> when I did
>>
>> err, s/changelink/br_stp_change_bridge_id/
>> the other options are set after register_netdevice, this is the only one
>> changed before
>>
>>> the rhashtable conversion, some of the options do fdb lookups as part of
>>> their routine
>>> but we don't have the table initialized yet at that point.
>>> I'll send a fix after some testing.
>>>
>>> Thanks,
>>> Nik
>>>
>>>
>>
>
> We need to fix this in -net, it has a memory leak that has existed since the
> introduction of br_stp_change_bridge_id() before register_netdevice because
> it adds an fdb entry which never gets deleted if an error happens, also the
> notifications for that fdb entry come with ifindex = 0 because the bridge
> netdev
> doesn't exist yet. All of that looks wrong, I'll send a fix for -net to move
> the bridge id change after the netdev register and cleanup any bridge fdbs
> on error.
>
> The commit with that change is:
> 30313a3d5794 ("bridge: Handle IFLA_ADDRESS correctly when creating bridge
> device")
> Before the changelink in while doing newlink in bridge was possible, this
> would happen
> only on netdev register fail, but now it is much easier to trigger (as below)
> since
> changelink can fail if called with wrong arguments.
>
One more thing before sending the patch, the actual commit that introduced the
fdb
insert in br_stp_change_bridge_id() is:
commit a4b816d8ba1c
Author: Toshiaki Makita <makita.toshi...@lab.ntt.co.jp>
Date: Fri Feb 7 16:48:21 2014 +0900
bridge: Change local fdb entries whenever mac address of bridge device
changes
So that is what we need to fix.
