Re: [Xen-devel] kasan_map_early_shadow() on Xen

From: Konrad Rzeszutek Wilk
Date: Tue Mar 03 2015 - 11:03:09 EST

On Tue, Mar 03, 2015 at 06:38:20PM +0300, Andrey Ryabinin wrote:
> 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).

If it is like that - then just using what had to be implemented
for the stack protection as a template ought to pave most of the
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