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Message-ID: <20240706080102.1cccb499@hermes.local>
Date: Sat, 6 Jul 2024 08:01:02 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: Jeongjun Park <aha310510@...il.com>
Cc: jiri@...nulli.us, syzbot+705c61d60b091ef42c04@...kaller.appspotmail.com,
davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
linux-kernel@...r.kernel.org, netdev@...r.kernel.org, pabeni@...hat.com,
syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH net,v2] team: Fix ABBA deadlock caused by race in
team_del_slave
On Sat, 6 Jul 2024 13:13:29 +0900
Jeongjun Park <aha310510@...il.com> wrote:
> CPU0 CPU1
> ---- ----
> lock(&rdev->wiphy.mtx);
> lock(team->team_lock_key#4);
> lock(&rdev->wiphy.mtx);
> lock(team->team_lock_key#4);
>
> Deadlock occurs due to the above scenario. Therefore, you can prevent
> deadlock by briefly releasing the lock before calling dev_open() in
> team_port_add() and locking it again after it returns.
>
> Reported-and-tested-by: syzbot+705c61d60b091ef42c04@...kaller.appspotmail.com
> Fixes: 3d249d4ca7d0 ("net: introduce ethernet teaming device")
> Signed-off-by: Jeongjun Park <aha310510@...il.com>
> ---
But if you drop the lock the actual data structures might have changed.
Usually not a good idea,
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