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Message-ID: <202008171222.3F206231E@keescook>
Date: Mon, 17 Aug 2020 12:24:29 -0700
From: Kees Cook <keescook@...omium.org>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
Cc: Alexander Popov <alex.popov@...ux.com>, Jann Horn <jannh@...gle.com>,
	Will Deacon <will@...nel.org>,
	Andrey Ryabinin <aryabinin@...tuozzo.com>,
	Alexander Potapenko <glider@...gle.com>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	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>,
	Masahiro Yamada <masahiroy@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Krzysztof Kozlowski <krzk@...nel.org>,
	Patrick Bellasi <patrick.bellasi@....com>,
	David Howells <dhowells@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Laura Abbott <labbott@...hat.com>, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	kasan-dev@...glegroups.com, linux-mm@...ck.org,
	kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org,
	notify@...nel.org, Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [PATCH RFC 2/2] lkdtm: Add heap spraying test

On Mon, Aug 17, 2020 at 01:24:37PM -0500, Eric W. Biederman wrote:
> Alexander Popov <alex.popov@...ux.com> writes:
> 
> > Add a simple test for CONFIG_SLAB_QUARANTINE.
> >
> > It performs heap spraying that aims to reallocate the recently freed heap
> > object. This technique is used for exploiting use-after-free
> > vulnerabilities in the kernel code.
> >
> > This test shows that CONFIG_SLAB_QUARANTINE breaks heap spraying
> > exploitation technique.
> >
> > Signed-off-by: Alexander Popov <alex.popov@...ux.com>
> 
> Why put this test in the linux kernel dump test module?
> 
> I have no problem with tests, and I may be wrong but this
> does not look like you are testing to see if heap corruption
> triggers a crash dump.  Which is what the rest of the tests
> in lkdtm are about.  Seeing if the test triggers successfully
> triggers a crash dump.

The scope of LKDTM has shifted a bit, and I'm fine with tests that
don't cause crashes as long as they're part of testing system-wide
defenses, etc. It's easier to collect similar tests together (even if
they don't break the system).

-- 
Kees Cook

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