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Message-ID: <CAGXu5jLiD1xEb=dDuf+_2JVzmkH_6O5-m=p=AVvi7qgQ+SV4UA@mail.gmail.com>
Date:	Fri, 15 Jul 2016 12:14:23 -0700
From:	Kees Cook <keescook@...omium.org>
To:	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>
Cc:	Balbir Singh <bsingharora@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Rik van Riel <riel@...hat.com>,
	Casey Schaufler <casey@...aufler-ca.com>,
	PaX Team <pageexec@...email.hu>,
	Brad Spengler <spender@...ecurity.net>,
	Russell King <linux@...linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	"David S. Miller" <davem@...emloft.net>,
	"x86@...nel.org" <x86@...nel.org>,
	Christoph Lameter <cl@...ux.com>,
	Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	Borislav Petkov <bp@...e.de>,
	Mathias Krause <minipli@...glemail.com>,
	Jan Kara <jack@...e.cz>, Vitaly Wool <vitalywool@...il.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Laura Abbott <labbott@...oraproject.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, linux-ia64@...r.kernel.org,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	sparclinux <sparclinux@...r.kernel.org>,
	linux-arch <linux-arch@...r.kernel.org>,
	Linux-MM <linux-mm@...ck.org>
Subject: Re: [kernel-hardening] Re: [PATCH v2 02/11] mm: Hardened usercopy

On Fri, Jul 15, 2016 at 12:00 PM, Daniel Micay <danielmicay@...il.com> wrote:
>> This could be a BUG, but I'd rather not panic the entire kernel.
>
> It seems unlikely that it will panic without panic_on_oops and that's
> an explicit opt-in to taking down the system on kernel logic errors
> exactly like this. In grsecurity, it calls the kernel exploit handling
> logic (panic if root, otherwise kill all process of that user and ban
> them until reboot) but that same logic is also called for BUG via oops
> handling so there's only really a distinction with panic_on_oops=1.
>
> Does it make sense to be less fatal for a fatal assertion that's more
> likely to be security-related? Maybe you're worried about having some
> false positives for the whitelisting portion, but I don't think those
> will lurk around very long with the way this works.

I'd like it to dump stack and be fatal to the process involved, but
yeah, I guess BUG() would work. Creating an infrastructure for
handling security-related Oopses can be done separately from this (and
I'd like to see that added, since it's a nice bit of configurable
reactivity to possible attacks).

-Kees

-- 
Kees Cook
Chrome OS & Brillo Security

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