From: Jann Horn <jannh@google.com>
To: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Petr Mladek <pmladek@suse.com>,
"Paul E. McKenney" <paulmck@kernel.org>,
Alexander Popov <alex.popov@linux.com>,
Jonathan Corbet <corbet@lwn.net>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Joerg Roedel <jroedel@suse.de>,
Maciej Rozycki <macro@orcam.me.uk>,
Muchun Song <songmuchun@bytedance.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Robin Murphy <robin.murphy@arm.com>,
Randy Dunlap <rdunlap@infradead.org>,
Lu Baolu <baolu.lu@linux.intel.com>,
Kees Cook <keescook@chromium.org>,
Luis Chamberlain <mcgrof@kernel.org>, Wei Liu <wl@xen.org>,
John Ogness <john.ogness@linutronix.de>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
Alexey Kardashevskiy <aik@ozlabs.ru>,
Christophe Leroy <christophe.leroy@csgroup.eu>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Mark Rutland <mark.rutland@arm.com>,
Andy Lutomirski <luto@kernel.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Garnier <thgarnie@google.com>,
Will Deacon <will.deacon@arm.com>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Laura Abbott <labbott@redhat.com>,
David S Miller <davem@davemloft.net>,
Borislav Petkov <bp@alien8.de>,
Kernel Hardening <kernel-hardening@lists.openwall.com>,
linux-hardening@vger.kernel.org,
"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
notify@kernel.org
Subject: Re: [PATCH] Introduce the pkill_on_warn boot parameter
Date: Wed, 27 Jul 2022 18:30:59 +0200 [thread overview]
Message-ID: <CAG48ez2Sh-kngNVeCF9-X550PQMaNnQaEvS+EAiWaDjWnmoHOg@mail.gmail.com> (raw)
In-Reply-To: <7c567acd-1cc1-a480-ca5a-d50a9c5a69ef@ispras.ru>
On Wed, Jul 27, 2022 at 6:17 PM Alexey Khoroshilov
<khoroshilov@ispras.ru> wrote:
> On 01.10.2021 22:59, Linus Torvalds wrote:
> Coming back to the discussion of WARN_ON()/pr_warn("WARNING:") semantics.
>
> We see a number of cases where WARNING is used to inform userspace that
> it is doing something wrong, e.g.
> https://elixir.bootlin.com/linux/v5.19-rc8/source/net/can/j1939/socket.c#L181
> https://elixir.bootlin.com/linux/v5.19-rc8/source/drivers/video/fbdev/core/fbmem.c#L1023
>
> It is definitely useful, but it does not make sense in case of fuzzing
> when the userspace should do wrong things and check if kernel behaves
> correctly.
>
> As a result we have warnings with two different intentions:
> - warn that something wrong happens in kernel, but we are able to continue;
> - warn userspace that it is doing something wrong.
>
> During fuzzing we would like to report the former and to ignore the
> latter. Are any ideas how these intentions can be recognized automatically?
https://elixir.bootlin.com/linux/v5.19-rc8/source/include/asm-generic/bug.h#L74
says:
* WARN(), WARN_ON(), WARN_ON_ONCE, and so on can be used to report
* significant kernel issues that need prompt attention if they should ever
* appear at runtime.
*
* Do not use these macros when checking for invalid external inputs
* (e.g. invalid system call arguments, or invalid data coming from
* network/devices), and on transient conditions like ENOMEM or EAGAIN.
* These macros should be used for recoverable kernel issues only.
* For invalid external inputs, transient conditions, etc use
* pr_err[_once/_ratelimited]() followed by dump_stack(), if necessary.
* Do not include "BUG"/"WARNING" in format strings manually to make these
* conditions distinguishable from kernel issues.
So if you see drivers intentionally using WARN() or printing
"WARNING:" on codepaths that are reachable with bogus inputs from
userspace, those codepaths should be fixed to log warnings in a
different format.
next prev parent reply other threads:[~2022-07-27 16:31 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-29 18:58 [PATCH] Introduce the pkill_on_warn boot parameter Alexander Popov
2021-09-29 19:01 ` Alexander Popov
2021-09-29 19:49 ` Paul E. McKenney
2021-09-30 9:15 ` Petr Mladek
2021-09-30 15:05 ` Alexander Popov
2021-10-01 12:23 ` Petr Mladek
2021-09-30 16:59 ` Steven Rostedt
2021-10-01 12:09 ` Petr Mladek
2021-09-30 18:28 ` Kees Cook
2021-10-01 19:59 ` Linus Torvalds
2021-10-02 11:41 ` Alexander Popov
2021-10-02 12:13 ` Steven Rostedt
2021-10-02 16:33 ` Alexander Popov
2021-10-02 16:52 ` Linus Torvalds
2021-10-02 21:05 ` Alexander Popov
2021-10-05 19:48 ` Eric W. Biederman
2021-10-06 14:56 ` Alexander Popov
2021-10-22 17:30 ` Alexander Popov
2022-07-27 16:17 ` Alexey Khoroshilov
2022-07-27 16:30 ` Jann Horn [this message]
2022-07-27 16:43 ` Alexey Khoroshilov
2022-07-27 16:42 ` Linus Torvalds
2022-07-27 17:47 ` Alexey Khoroshilov
2021-09-29 23:31 ` Andrew Morton
2021-09-30 18:27 ` Alexander Popov
2021-09-30 18:36 ` Kees Cook
2021-09-29 19:03 ` Dave Hansen
2021-09-29 19:47 ` Peter Zijlstra
2021-09-29 20:06 ` Kees Cook
2021-09-30 13:55 ` Alexander Popov
2021-09-30 18:20 ` Kees Cook
2021-10-02 18:04 ` Al Viro
2021-10-02 18:31 ` Steven Rostedt
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=CAG48ez2Sh-kngNVeCF9-X550PQMaNnQaEvS+EAiWaDjWnmoHOg@mail.gmail.com \
--to=jannh@google.com \
--cc=aik@ozlabs.ru \
--cc=akpm@linux-foundation.org \
--cc=alex.popov@linux.com \
--cc=andriy.shevchenko@linux.intel.com \
--cc=ard.biesheuvel@linaro.org \
--cc=baolu.lu@linux.intel.com \
--cc=bp@alien8.de \
--cc=christophe.leroy@csgroup.eu \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=davem@davemloft.net \
--cc=gregkh@linuxfoundation.org \
--cc=john.ogness@linutronix.de \
--cc=jroedel@suse.de \
--cc=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=khoroshilov@ispras.ru \
--cc=labbott@redhat.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-hardening@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=luto@kernel.org \
--cc=macro@orcam.me.uk \
--cc=mark.rutland@arm.com \
--cc=mcgrof@kernel.org \
--cc=notify@kernel.org \
--cc=paulmck@kernel.org \
--cc=peterz@infradead.org \
--cc=pmladek@suse.com \
--cc=rdunlap@infradead.org \
--cc=robin.murphy@arm.com \
--cc=rostedt@goodmis.org \
--cc=songmuchun@bytedance.com \
--cc=tglx@linutronix.de \
--cc=thgarnie@google.com \
--cc=torvalds@linux-foundation.org \
--cc=viresh.kumar@linaro.org \
--cc=will.deacon@arm.com \
--cc=wl@xen.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).