From: Oleksij Rempel <o.rempel@pengutronix.de>
To: Ziqi Zhao <astrajoan@yahoo.com>
Cc: ivan.orlov0322@gmail.com, edumazet@google.com,
syzbot+881d65229ca4f9ae8c84@syzkaller.appspotmail.com,
socketcan@hartkopp.net, bridge@lists.linux-foundation.org,
nikolay@nvidia.com,
syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com,
roopa@nvidia.com, kuba@kernel.org, pabeni@redhat.com,
arnd@arndb.de, syzkaller-bugs@googlegroups.com,
mudongliangabcd@gmail.com, linux-can@vger.kernel.org,
mkl@pengutronix.de, skhan@linuxfoundation.org, robin@protonic.nl,
linux-kernel@vger.kernel.org, linux@rempel-privat.de,
kernel@pengutronix.de, netdev@vger.kernel.org,
davem@davemloft.net
Subject: Re: [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock
Date: Fri, 17 Nov 2023 09:10:02 +0100 [thread overview]
Message-ID: <20231117081002.GA590719@pengutronix.de> (raw)
In-Reply-To: <20230807044634.GA5736@pengutronix.de>
On Mon, Aug 07, 2023 at 06:46:34AM +0200, Oleksij Rempel wrote:
> On Fri, Jul 21, 2023 at 09:22:26AM -0700, Ziqi Zhao wrote:
> > The following 3 locks would race against each other, causing the
> > deadlock situation in the Syzbot bug report:
> >
> > - j1939_socks_lock
> > - active_session_list_lock
> > - sk_session_queue_lock
> >
> > A reasonable fix is to change j1939_socks_lock to an rwlock, since in
> > the rare situations where a write lock is required for the linked list
> > that j1939_socks_lock is protecting, the code does not attempt to
> > acquire any more locks. This would break the circular lock dependency,
> > where, for example, the current thread already locks j1939_socks_lock
> > and attempts to acquire sk_session_queue_lock, and at the same time,
> > another thread attempts to acquire j1939_socks_lock while holding
> > sk_session_queue_lock.
> >
> > NOTE: This patch along does not fix the unregister_netdevice bug
> > reported by Syzbot; instead, it solves a deadlock situation to prepare
> > for one or more further patches to actually fix the Syzbot bug, which
> > appears to be a reference counting problem within the j1939 codebase.
> >
> > Reported-by: syzbot+1591462f226d9cbf0564@syzkaller.appspotmail.com
> > Signed-off-by: Ziqi Zhao <astrajoan@yahoo.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
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next prev parent reply other threads:[~2023-11-17 8:10 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-07-04 6:19 [syzbot] [can?] possible deadlock in j1939_sk_errqueue (2) syzbot
2023-07-04 6:47 ` [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Ziqi Zhao
2023-07-04 6:47 ` syzbot
2023-07-04 7:37 ` Oleksij Rempel
2023-07-21 16:22 ` Ziqi Zhao
2023-07-23 15:41 ` Oleksij Rempel
2023-08-07 4:46 ` Oleksij Rempel
2023-11-17 8:10 ` Oleksij Rempel [this message]
2023-07-10 17:53 ` [syzbot] [can?] possible deadlock in j1939_sk_errqueue (2) syzbot
2023-07-12 0:47 ` [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Ziqi Zhao
2023-07-12 1:16 ` [syzbot] [can?] possible deadlock in j1939_sk_errqueue (2) syzbot
2023-07-13 22:23 ` [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Stephen Hemminger
2023-11-15 3:54 ` [syzbot] [can?] possible deadlock in j1939_sk_errqueue (2) syzbot
[not found] <C29A816B-6E28-4A36-AE59-F446180C910B.ref@yahoo.com>
2023-07-14 5:58 ` [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Astra Joan
[not found] <8A7EE4B2-4DCE-40FF-B971-F67F402872BB.ref@yahoo.com>
2023-07-07 4:39 ` Astra Joan
[not found] <F17EC83C-9D70-463A-9C46-FBCC53A1F13C.ref@yahoo.com>
2023-07-04 17:55 ` Astra Joan
2023-07-05 4:39 ` Oleksij Rempel
2023-07-05 4:50 ` Dmitry Vyukov
-- strict thread matches above, loose matches on Subject: below --
2023-06-21 8:46 [syzbot] [net?] unregister_netdevice: waiting for DEV to become free (8) Dongliang Mu
2023-06-26 5:50 ` [PATCH] can: j1939: prevent deadlock by changing j1939_socks_lock to rwlock Ziqi Zhao
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