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Date: Wed, 21 Jan 2015 19:22:42 -0500
From: Sasha Levin <sasha.levin@oracle.com>
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To: Andrey Ryabinin <a.ryabinin@samsung.com>, linux-kernel@vger.kernel.org
CC: Dmitry Vyukov <dvyukov@google.com>, Konstantin Serebryany <kcc@google.com>,
        Dmitry Chernenkov <dmitryc@google.com>,
        Andrey Konovalov <adech.fo@gmail.com>,
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        Michal Marek <mmarek@suse.cz>, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Christoph Lameter <cl@linux.com>,
        Pekka Enberg <penberg@kernel.org>,
        David Rientjes <rientjes@google.com>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Dave Hansen <dave.hansen@intel.com>, Andi Kleen <andi@firstfloor.org>,
        Vegard Nossum <vegard.nossum@gmail.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org, linux-mm@kvack.org,
        Randy Dunlap <rdunlap@infradead.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
        Dave Jones <davej@redhat.com>, Jonathan Corbet <corbet@lwn.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v9 00/17]  Kernel address sanitizer - runtime memory debugger.
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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