netdev - Re: [PATCH] can: j1939: prevent deadlock by changing j1939_socks

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Date: Tue, 4 Jul 2023 10:55:47 -0700
From: Astra Joan <astrajoan@...oo.com>
To: o.rempel@...gutronix.de
Cc: Astra Joan <astrajoan@...oo.com>,
 davem@...emloft.net,
 edumazet@...gle.com,
 ivan.orlov0322@...il.com,
 kernel@...gutronix.de,
 kuba@...nel.org,
 linux-can@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 linux@...pel-privat.de,
 mkl@...gutronix.de,
 netdev@...r.kernel.org,
 pabeni@...hat.com,
 robin@...tonic.nl,
 skhan@...uxfoundation.org,
 socketcan@...tkopp.net,
 syzbot+1591462f226d9cbf0564@...kaller.appspotmail.com,
 syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock
 to rwlock

Hi Oleksij,

Thank you for providing help with the bug fix! The patch was created
when I was working on another bug:

https://syzkaller.appspot.com/bug?extid=881d65229ca4f9ae8c84

But the patch was not a direct fix of the problem reported in the
unregister_netdevice function call. Instead, it suppresses potential
deadlock information to guarantee the real bug would show up. Since I
have verified that the patch resolved a deadlock situation involving
the exact same locks, I'm pretty confident it would be a proper fix for
the current bug in this thread.

I'm not sure, though, about how I could instruct Syzbot to create a
reproducer to properly test this patch. Could you or anyone here help
me find the next step? Thank you so much!

Best regards,
Ziqi