linux-kernel - Re: BUG: workqueue lockup (2)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201805131106.GFF73973.OOtMVQFSFOJFHL@I-love.SAKURA.ne.jp>
Date:   Sun, 13 May 2018 11:06:17 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     ebiggers3@...il.com,
        bot+e38be687a2450270a3b593bacb6b5795a7a74edb@...kaller.appspotmail.com,
        peter@...leysoftware.com
Cc:     dvyukov@...gle.com, gregkh@...uxfoundation.org,
        kstewart@...uxfoundation.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, pombredanne@...b.com,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de
Subject: Re: BUG: workqueue lockup (2)

Eric Biggers wrote:
> The bug that this reproducer reproduces was fixed a while ago by commit
> 966031f340185e, so I'm marking this bug report fixed by it:
> 
> #syz fix: n_tty: fix EXTPROC vs ICANON interaction with TIOCINQ (aka FIONREAD)

Nope. Commit 966031f340185edd ("n_tty: fix EXTPROC vs ICANON interaction with
TIOCINQ (aka FIONREAD)") is "Wed Dec 20 17:57:06 2017 -0800" but the last
occurrence on linux.git (commit 008464a9360e31b1 ("Merge branch 'for-linus' of
git://git.kernel.org/pub/scm/linux/kernel/git/jikos/hid")) is only a few days ago
("Wed May 9 10:49:52 2018 -1000").

> 
> Note that the error message was not always "BUG: workqueue lockup"; it was also
> sometimes like "watchdog: BUG: soft lockup - CPU#5 stuck for 22s!".
> 
> syzbot still is hitting the "BUG: workqueue lockup" error sometimes, but it must
> be for other reasons.  None has a reproducer currently.

The last occurrence on linux.git is considered as a duplicate of

  [upstream] INFO: rcu detected stall in n_tty_receive_char_special
  https://syzkaller.appspot.com/bug?id=3d7481a346958d9469bebbeb0537d5f056bdd6e8

which we already have a reproducer at
https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/YCVPocx3AgAJ
and debug output is available at
https://groups.google.com/d/msg/syzkaller-bugs/O4DbPiJZFBY/TxQ7WS5ZAwAJ .

We are currently waiting for comments from Peter Hurley who added that code.