From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Petr Mladek <pmladek@suse.com>,
Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
LKML <linux-kernel@vger.kernel.org>,
syzkaller <syzkaller@googlegroups.com>
Subject: Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..."
Date: Sat, 16 Mar 2019 19:18:50 +0900 [thread overview]
Message-ID: <f015f007-2402-27a0-1694-93b1bcffe84b@i-love.sakura.ne.jp> (raw)
In-Reply-To: <CACT4Y+ZBpfLpk0FRp7O8Ut=mmf-uddK_fLMDHtPkf6FnMGMqPA@mail.gmail.com>
On 2019/03/16 18:11, Dmitry Vyukov wrote:
> Such reports showed up always with low frequency. For all that I
> looked at we also always had a normal non-truncated version, so I was
> never too worried.
>
> If something would write from userspace, that would show up in the
> output, or not?
>
> Perhaps syzkaller somehow manages to lower console output level?
panic() calls console_verbose() before calling
pr_emerg("Kernel panic - not syncing: %s\n", buf);
line. Then, someone might have changed console_loglevel enough to
suppress printk() output.
> I figured out that we should restrict it from doing
> syslog(SYSLOG_ACTION_CONSOLE_OFF). And I also restricted its access o
> /dev/console. But maybe there is something else? It _should_ not be
> able to write to random sysctl's.
Maybe try running with "ignore_loglevel" kernel command line option added?
next prev parent reply other threads:[~2019-03-16 10:20 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-16 2:09 [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." Tetsuo Handa
2019-03-16 9:11 ` Dmitry Vyukov
2019-03-16 10:18 ` Tetsuo Handa [this message]
2019-03-16 14:14 ` Sergey Senozhatsky
2019-03-16 14:16 ` Dmitry Vyukov
2019-03-16 14:40 ` Sergey Senozhatsky
2019-03-16 14:53 ` Tetsuo Handa
2019-03-16 14:57 ` Dmitry Vyukov
2019-03-16 15:02 ` Tetsuo Handa
2019-03-16 15:10 ` Dmitry Vyukov
2019-03-18 5:27 ` Tetsuo Handa
2019-03-18 12:07 ` Dmitry Vyukov
2019-03-18 12:32 ` Dmitry Vyukov
2019-03-18 12:39 ` Dmitry Vyukov
2019-03-19 0:41 ` Tetsuo Handa
2019-03-18 12:50 ` Sergey Senozhatsky
2019-03-18 13:42 ` Dmitry Vyukov
2019-03-18 14:09 ` Sergey Senozhatsky
2019-03-19 8:10 ` Dmitry Vyukov
2019-03-19 12:35 ` Sergey Senozhatsky
2019-03-19 13:35 ` Dmitry Vyukov
2019-05-08 10:31 ` Tetsuo Handa
2019-05-09 9:58 ` Sergey Senozhatsky
2019-05-09 10:18 ` Sergey Senozhatsky
2019-05-09 10:40 ` Tetsuo Handa
2019-05-09 10:26 ` Tetsuo Handa
2019-05-09 10:36 ` Sergey Senozhatsky
2019-05-10 14:12 ` Petr Mladek
2019-05-10 14:53 ` Tetsuo Handa
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=f015f007-2402-27a0-1694-93b1bcffe84b@i-love.sakura.ne.jp \
--to=penguin-kernel@i-love.sakura.ne.jp \
--cc=dvyukov@google.com \
--cc=linux-kernel@vger.kernel.org \
--cc=pmladek@suse.com \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=sergey.senozhatsky@gmail.com \
--cc=syzkaller@googlegroups.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.