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Date: Tue, 03 Mar 2015 18:38:20 +0300
From: Andrey Ryabinin <a.ryabinin@samsung.com>
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To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: "Luis R. Rodriguez" <mcgrof@suse.com>,
        Jeremy Fitzhardinge <jeremy@goop.org>,
        Rusty Russell <rusty@rustcorp.com.au>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Andy Lutomirski <luto@amacapital.net>,
        Chris Wright <chrisw@sous-sol.org>, xen-devel@lists.xenproject.org,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        virtualization@lists.linux-foundation.org,
        Alok Kataria <akataria@vmware.com>
Subject: Re: [Xen-devel] kasan_map_early_shadow() on Xen
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On 03/03/2015 05:16 PM, Konrad Rzeszutek Wilk wrote:
> On Tue, Mar 03, 2015 at 04:15:06PM +0300, Andrey Ryabinin wrote:
>> On 03/03/2015 12:40 PM, Luis R. Rodriguez wrote:
>>> Andrey,
>>>
>>> I believe that on Xen we should disable kasan, would like confirmation
>>
>> I guess Xen guests won't work with kasan because Xen guests doesn't setup shadow
>> (kasan_map_early_shadow() is not called in xen guests).
>>
>> Disabling kasan for Xen in Kconfig is undesirable because that will disable kasan
>> for allmodconfig and allyesconfig builds, but I don't see other option for now.
> 
> Was there an bug reported for this? It would be good to CC the maintainers
> of Xen on that sort of thing.
> 

There was no report for this. I just looked at Xen code because of this Luis's mail
and I don't see how it could work with kasan.
Fixing this might be not trivial. We need to setup shadow memory before any kasan instrumented
function will run.
This is like with -fstack-protector (you need to setup gdt before calling any stack protected function).