From: Michal Hocko <mhocko@kernel.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Kees Cook <keescook@chromium.org>, Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Hellstrom <thellstrom@vmware.com>,
Daniel Micay <danielmicay@gmail.com>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] kref: Avoid null pointer dereference after WARN
Date: Wed, 28 Jun 2017 13:26:04 +0200 [thread overview]
Message-ID: <20170628112604.GA5234@dhcp22.suse.cz> (raw)
In-Reply-To: <20170627192939.GJ23705@tassilo.jf.intel.com>
On Tue 27-06-17 12:29:39, Andi Kleen wrote:
> On Tue, Jun 27, 2017 at 09:11:28PM +0200, Jason A. Donenfeld wrote:
[...]
> > The bigger question, though, is the value of these checks in the first
> > place. Has anybody written a coccinelle check to look into this
> > statically? Has it historically been a useful thing for driver
> > developers to have? Is it good defense in depth or is it overkill? At
> > the very least, the original authors of kref thought a WARN_ON was
> > warranted, which means probably a BUG_ON is a sensible fix, until
> > somebody does the work of investigating these more careful questions.
>
> Right that's the question that should have been answered before
> this patch.
>
> I don't think it was ever intended to be a defense, just as a hint
> for driver developers.
>
> My suspicion is that they're mostly useless.
Completely agreed here!
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2017-06-28 11:26 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-06-27 3:52 [PATCH] kref: Avoid null pointer dereference after WARN Kees Cook
2017-06-27 7:06 ` Greg Kroah-Hartman
2017-06-27 11:00 ` Jason A. Donenfeld
2017-06-27 14:49 ` Andi Kleen
2017-06-27 19:11 ` Jason A. Donenfeld
2017-06-27 19:29 ` Andi Kleen
2017-06-28 11:26 ` Michal Hocko [this message]
2017-06-27 18:34 ` Kees Cook
2017-07-05 15:37 ` Peter Zijlstra
2017-06-28 11:57 ` Greg Kroah-Hartman
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