linux-kernel - Re: [PATCH 5/6] notifiers: Use CHECK_DATA

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Date:   Wed, 22 Mar 2017 12:55:00 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Arjan van de Ven <arjan@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Rik van Riel <riel@...hat.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Jakub Kicinski <jakub.kicinski@...ronome.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Olof Johansson <olof@...om.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 5/6] notifiers: Use CHECK_DATA_CORRUPTION() on checks

On Wed, Mar 22, 2017 at 12:32 PM, Arjan van de Ven
<arjan@...ux.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