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From: Kees Cook <keescook@chromium.org>
Date: Wed, 22 Mar 2017 12:55:00 -0700
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Subject: Re: [PATCH 5/6] notifiers: Use CHECK_DATA_CORRUPTION() on checks
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        Jakub Kicinski <jakub.kicinski@netronome.com>,
        Viresh Kumar <viresh.kumar@linaro.org>, Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Dmitry Vyukov <dvyukov@google.com>, Olof Johansson <olof@lixom.net>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        LKML <linux-kernel@vger.kernel.org>,
        "kernel-hardening@lists.openwall.com" 
        <kernel-hardening@lists.openwall.com>
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On Wed, Mar 22, 2017 at 12:32 PM, Arjan van de Ven
<arjan@linux.intel.com> wrote:
> On 3/22/2017 12:29 PM, Kees Cook wrote:
>>>
>>> When performing notifier function pointer sanity checking, allow
>>> CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG.
>>> Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting
>>> CONFIG_BUG_ON_DATA_CORRUPTION.
>
>
>> Any feedback on this change? By default, this retains the existing
>> WARN behavior...
>
>
> if you're upgrading, is the end point really a panic() ?
> e.g. do you assume people to also set panic-on-oops?

That's one option, yes. With the BUG, the process associated is killed
(which is the first level of defense upgrade), and if a system is also
set to panic-on-oops, the entire system will panic (and usually such
systems also retain their crash consoles in some fashion for later
analysis, etc).

-Kees

-- 
Kees Cook
Pixel Security