From: Kees Cook <keescook@chromium.org>
To: Willy Tarreau <w@1wt.eu>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Paul Gortmaker <paul.gortmaker@windriver.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Andrew Morton <akpm@linux-foundation.org>,
Antonio SJ Musumeci <trapexit@spawn.link>,
Miklos Szeredi <miklos@szeredi.hu>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
stable <stable@vger.kernel.org>
Subject: Re: BUG_ON() in workingset_node_shadows_dec() triggers
Date: Fri, 7 Oct 2016 10:16:42 -0700 [thread overview]
Message-ID: <CAGXu5jLTo+QY9YuEKYbACXdnAXgnQdPPnPejYtiSeg4j5XW-Fw@mail.gmail.com> (raw)
In-Reply-To: <20161007054824.GA9917@1wt.eu>
On Thu, Oct 6, 2016 at 10:48 PM, Willy Tarreau <w@1wt.eu> wrote:
> On Thu, Oct 06, 2016 at 04:59:20PM -0700, Linus Torvalds wrote:
>> We should just switch BUG() over and be done with it. The whole point
>> it that since it should never trigger in the first place, the
>> semantics on BUG() should never matter.
>>
>> And if you have some code that depends on the semantics of BUG(), that
>> code is buggy crap *by*definition*.
>
> I totally agree with this. If a developer writes BUG() somewhere, it
> means he doesn't see how it is possible to end up in this situation.
> Thus we cannot hope that the BUG() call is doing anything right to
> fix what the code author didn't expect to happen. It just means
> "try to limit the risks but I don't really know which ones".
>
> Also we won't make things worse. Where people currently have an oops,
> they'll get one or more warnings. The side effects (lockups, panic,
> etc) will more or less be the same, but many of us already don't want
> to continue after an oops and despite this our systems work fine, so
> I don't see why anyone would suffer from such a change. However some
> developers may get more details about issues than what they could get
> in the past.
Fair enough. I'll put something together for at least my use-cases and
see how ugly it gets in testing. :) I actually started on something
like this for the CONFIG_DEBUG_LIST, which had to deal with the logic
of "continue after WARN or abort after BUG" etc...
Regardless, I still think that we can't let BUG continue kernel
execution though, since it may lead to entirely unexpected behavior
(possibly security-sensitive) by still running. Upgrading BUG to
panic(), though, I'd be fine with, as a way to get people to convert
to WARN.
-Kees
--
Kees Cook
Nexus Security
next prev parent reply other threads:[~2016-10-07 17:16 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-04 4:00 BUG_ON() in workingset_node_shadows_dec() triggers Linus Torvalds
2016-10-04 4:07 ` Andrew Morton
2016-10-04 4:12 ` Linus Torvalds
2016-10-04 7:03 ` Raymond Jennings
2016-10-04 16:03 ` Linus Torvalds
2016-10-04 8:02 ` Greg KH
2016-10-04 9:32 ` Johannes Weiner
2016-10-05 1:21 ` Linus Torvalds
2016-10-05 9:25 ` Johannes Weiner
2016-10-05 9:31 ` Johannes Weiner
2016-10-05 10:40 ` Jan Kara
2016-10-05 16:10 ` Linus Torvalds
2016-10-05 17:00 ` [PATCH] checkpatch: extend BUG warning Joe Perches
2016-10-05 17:07 ` Linus Torvalds
2016-10-05 2:43 ` BUG_ON() in workingset_node_shadows_dec() triggers Paul Gortmaker
2016-10-05 3:29 ` Linus Torvalds
2016-10-05 5:44 ` Willy Tarreau
2016-10-05 15:52 ` Linus Torvalds
2016-10-05 19:06 ` Willy Tarreau
2016-10-05 19:18 ` Linus Torvalds
2016-10-05 21:09 ` Willy Tarreau
2016-10-05 21:14 ` Kees Cook
2016-10-05 21:46 ` Linus Torvalds
2016-10-05 22:17 ` Kees Cook
2016-10-05 22:29 ` Linus Torvalds
2016-10-06 22:07 ` Kees Cook
2016-10-06 22:29 ` Linus Torvalds
2016-10-06 23:05 ` Kees Cook
2016-10-06 23:59 ` Linus Torvalds
2016-10-07 5:48 ` Willy Tarreau
2016-10-07 17:16 ` Kees Cook [this message]
2016-10-07 17:21 ` Linus Torvalds
2016-10-07 17:33 ` Kees Cook
2016-10-07 18:26 ` Willy Tarreau
2016-10-06 1:59 ` Dave Chinner
2016-10-06 2:12 ` Linus Torvalds
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