linux-kernel - Re: [RFC/PATCH RESEND -next 00/21] Address sanitizer for kernel (kasan)

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Message-id: <53BE9C53.5090301@samsung.com>
Date:	Thu, 10 Jul 2014 17:59:47 +0400
From:	Andrey Ryabinin <a.ryabinin@...sung.com>
To:	Vegard Nossum <vegard.nossum@...il.com>,
	Andi Kleen <andi@...stfloor.org>
Cc:	Dave Hansen <dave.hansen@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	Dmitry Vyukov <dvyukov@...gle.com>,
	Konstantin Serebryany <kcc@...gle.com>,
	Alexey Preobrazhensky <preobr@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Yuri Gribov <tetra2005@...il.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Sasha Levin <sasha.levin@...cle.com>,
	Michal Marek <mmarek@...e.cz>,
	Russell King <linux@....linux.org.uk>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.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>,
	kbuild <linux-kbuild@...r.kernel.org>,
	linux-arm-kernel@...ts.infradead.org,
	x86 maintainers <x86@...nel.org>,
	Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [RFC/PATCH RESEND -next 00/21] Address sanitizer for kernel
 (kasan) - dynamic memory error detector.

On 07/10/14 01:59, Vegard Nossum wrote:
> On 9 July 2014 23:44, Andi Kleen <andi@...stfloor.org> wrote:
>> Dave Hansen <dave.hansen@...el.com> writes:
>>>
>>> You're also claiming that "KASAN is better than all of
>>
>> better as in finding more bugs, but surely not better as in
>> "do so with less overhead"
>>
>>> CONFIG_DEBUG_PAGEALLOC".  So should we just disallow (or hide)
>>> DEBUG_PAGEALLOC on kernels where KASAN is available?
>>
>> I don't think DEBUG_PAGEALLOC/SLUB debug and kasan really conflict.
>>
>> DEBUG_PAGEALLOC/SLUB is "much lower overhead but less bugs found".
>> KASAN is "slow but thorough" There are niches for both.
>>
>> But I could see KASAN eventually deprecating kmemcheck, which
>> is just incredible slow.
> 
> FWIW, I definitely agree with this -- if KASAN can do everything that
> kmemcheck can, it is no doubt the right way forward.
> 

AFAIK kmemcheck could catch reads of uninitialized memory.
KASAN can't do it now, but It should be possible to implementation.
There is such tool for userspace - https://code.google.com/p/memory-sanitizer/wiki/MemorySanitizer

However detection of reads of uninitialized  memory will require a different
shadow encoding. Therefore I think it would be better to make it as a separate feature, incompatible with kasan.



> 
> Vegard
> 

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