linux-kernel - Re: [PATCH net] rtnetlink: fix possible deadlock in team_port_change

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Message-Id: <AB56B530-B67F-4A41-99E7-1FDA14604D5F@gmail.com>
Date: Wed, 31 Jul 2024 10:37:38 +0900
From: Jeongjun Park <aha310510@...il.com>
To: Jakub Kicinski <kuba@...nel.org>
Cc: davem@...emloft.net, edumazet@...gle.com, pabeni@...hat.com,
 idosch@...dia.com, jiri@...nulli.us, amcohen@...dia.com, liuhangbin@...il.com,
 netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 syzbot+b668da2bc4cb9670bf58@...kaller.appspotmail.com
Subject: Re: [PATCH net] rtnetlink: fix possible deadlock in team_port_change_check



> 2024. 7. 31. 오전 8:59, Jakub Kicinski <kuba@...nel.org> 작성:
> 
> On Wed, 31 Jul 2024 00:22:10 +0900 Jeongjun Park wrote:
>> do_setlink() changes the flag of the device and then enslaves it. However,
>> in this case, if the IFF_UP flag is set, the enslavement process calls
>> team_add_slave() to acquire 'team->lock', but when dev_open() opens the
>> newly enslaved device, the NETDEV_UP event occurs, and as a result,
>> a deadlock occurs when team_port_change_check() tries to acquire
>> 'team->lock' again.
> 
> You can't change behavior like this, see ec4ffd100ffb396ec

Okay. In that case, I'll write a patch that modifies the code of the team driver and send
it back to you.

Regards,
Jeongjun Park