linux-kernel - Re: [PATCH v9 00/17] Kernel address sanitizer

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Date:	Wed, 21 Jan 2015 19:22:42 -0500
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Andrey Ryabinin <a.ryabinin@...sung.com>,
	linux-kernel@...r.kernel.org
CC:	Dmitry Vyukov <dvyukov@...gle.com>,
	Konstantin Serebryany <kcc@...gle.com>,
	Dmitry Chernenkov <dmitryc@...gle.com>,
	Andrey Konovalov <adech.fo@...il.com>,
	Yuri Gribov <tetra2005@...il.com>,
	Konstantin Khlebnikov <koct9i@...il.com>,
	Michal Marek <mmarek@...e.cz>,
	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>,
	Dave Hansen <dave.hansen@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Vegard Nossum <vegard.nossum@...il.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-mm@...ck.org, Randy Dunlap <rdunlap@...radead.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Dave Jones <davej@...hat.com>,
	Jonathan Corbet <corbet@....net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH v9 00/17]  Kernel address sanitizer - runtime memory debugger.

On 01/21/2015 11:51 AM, Andrey Ryabinin wrote:
> Changes since v8:
> 	- Fixed unpoisoned redzones for not-allocated-yet object
> 	    in newly allocated slab page. (from Dmitry C.)
> 
> 	- Some minor non-function cleanups in kasan internals.
> 
> 	- Added ack from Catalin
> 
> 	- Added stack instrumentation. With this we could detect
> 	    out of bounds accesses in stack variables. (patch 12)
> 
> 	- Added globals instrumentation - catching out of bounds in
> 	    global varibles. (patches 13-17)
> 
> 	- Shadow moved out from vmalloc into hole between vmemmap
> 	    and %esp fixup stacks. For globals instrumentation
> 	    we will need shadow backing modules addresses.
> 	    So we need some sort of a shadow memory allocator
> 	    (something like vmmemap_populate() function, except
> 	    that it should be available after boot).
> 
> 	    __vmalloc_node_range() suits that purpose, except that
> 	    it can't be used for allocating for shadow in vmalloc
> 	    area because shadow in vmalloc is already 'allocated'
> 	    to protect us from other vmalloc users. So we need
> 	    16TB of unused addresses. And we have big enough hole
> 	    between vmemmap and %esp fixup stacks. So I moved shadow
> 	    there.

I'm not sure which new addition caused it, but I'm getting tons of
false positives from platform drivers trying to access memory they
don't "own" - because they expect to find hardware there.

I suspect we'd need to mark that memory region somehow to prevent
accesses to it from triggering warnings?


Thanks,
Sasha
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