Re: [syzbot ci] Re: net: move netdev_compute_master_upper_features to ndo_set_features

On 3/11/26 10:18 PM, Sabrina Dubroca wrote:
> 2026-03-11, 00:47:41 +0000, Hangbin Liu wrote:
>> On Tue, Mar 10, 2026 at 08:17:01PM +0100, Sabrina Dubroca wrote:
>>> 2026-03-10, 10:02:09 -0700, syzbot ci wrote:
>>>> batman_adv: batadv0: Not using interface batadv_slave_1 (retrying later): interface not active
>>>> hsr_slave_0: entered promiscuous mode
>>>> hsr_slave_1: entered promiscuous mode
>>>> ------------[ cut here ]------------
>>>> err == -EMSGSIZE
>>>> WARNING: net/core/rtnetlink.c:4421 at rtmsg_ifinfo_build_skb+0x218/0x260, CPU#0: syz-executor/6496
>>>
>>> I'm not sure this one is caused by this series, but either way,
>>
>>
>>  rtnetlink_event+0x1b7/0x270
>>  notifier_call_chain+0x1be/0x400
>>  netdev_change_features+0x95/0xe0
>>  __netdev_upper_dev_link+0xb20/0xc80
>>  netdev_upper_dev_link+0xb0/0x100
>>
>>
>> This patch calls netdev_change_features() after __netdev_upper_dev_link(),
>> Which trigger a NETDEV_FEAT_CHANGE notify and calls rtmsg_ifinfo_event()
>> to fill the new link info. Maybe the event is a bit early and macsec has
>> data not ready?
> 
> But this would still mean that there's a mismatch between
> if_nlmsg_size() and rtnl_fill_ifinfo(), and your patch is only
> revealing it.
> 
> I'll send fixes for the stuff I mentioned, no idea if that's what
> syzbot saw since we don't have a repro.

It looks like even the nipa CI is reproducing the issue, i.e.:

https://netdev-ctrl.bots.linux.dev/logs/vmksft/net-dbg/results/554921/17-rtnetlink-sh/

more failures here:

https://netdev.bots.linux.dev/contest.html?pw-n=0&branch=net-next-2026-03-12--06-00&pw-n=0&pass=0

the fail in mascsec-offload looks quite deterministic, could you please
have a look?

/P