Re: [PATCH v6 0/6] KASAN for arm64

[Catalin Marinas]

On Thu, Oct 08, 2015 at 02:09:26PM +0200, Ard Biesheuvel wrote:
> On 8 October 2015 at 13:23, Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx> wrote:
> > On 10/08/2015 02:11 PM, Mark Rutland wrote:
> >> On Thu, Oct 08, 2015 at 01:36:09PM +0300, Andrey Ryabinin wrote:
> >>> 2015-10-07 13:04 GMT+03:00 Catalin Marinas <catalin.marinas@xxxxxxx>:
> >>>> On Thu, Sep 17, 2015 at 12:38:06PM +0300, Andrey Ryabinin wrote:
> >>>>> As usual patches available in git
> >>>>>       git://github.com/aryabinin/linux.git kasan/arm64v6
> >>>>>
> >>>>> Changes since v5:
> >>>>>  - Rebase on top of 4.3-rc1
> >>>>>  - Fixed EFI boot.
> >>>>>  - Updated Doc/features/KASAN.
> >>>>
> >>>> I tried to merge these patches (apart from the x86 one which is already
> >>>> merged) but it still doesn't boot on Juno as an EFI application.
> >>>>
> >>>
> >>> 4.3-rc1 was ok and 4.3-rc4 is not. Break caused by 0ce3cc008ec04
> >>> ("arm64/efi: Fix boot crash by not padding between EFI_MEMORY_RUNTIME
> >>> regions")
> >>> It introduced sort() call in efi_get_virtmap().
> >>> sort() is generic kernel function and it's instrumented, so we crash
> >>> when KASAN tries to access shadow in sort().
> >>
> >> I believe this is solved by Ard's stub isolation series [1,2], which
> >> will build a stub-specific copy of sort() and various other functions
> >> (see the arm-deps in [2]).
> >>
> >> So long as the stub is not built with ASAN, that should work.
> >
> > Thanks, this should help, as we already build the stub without ASAN instrumentation.
> 
> Indeed. I did not mention instrumentation in the commit log for those
> patches, but obviously, something like KASAN instrumentation cannot be
> tolerated in the stub since it makes assumptions about the memory
> layout

I'll review your latest EFI stub isolation patches and try Kasan again
on top (most likely tomorrow).

Thanks.

-- 
Catalin
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