[PATCH 19/35] kasan: don't allow SW_TAGS with ARM64_MTE

[Andrey Konovalov]

On Thu, Aug 27, 2020 at 11:52 AM Vincenzo Frascino
<vincenzo.frascino at arm.com> wrote:
>
> Hi Andrey,
>
> On 8/27/20 9:04 AM, Catalin Marinas wrote:
> > On Fri, Aug 14, 2020 at 07:27:01PM +0200, Andrey Konovalov wrote:
> >> Software tag-based KASAN provides its own tag checking machinery that
> >> can conflict with MTE. Don't allow enabling software tag-based KASAN
> >> when MTE is enabled.
> >>
> >> Signed-off-by: Andrey Konovalov <andreyknvl at google.com>
> >> ---
> >>  lib/Kconfig.kasan | 1 +
> >>  1 file changed, 1 insertion(+)
> >>
> >> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> >> index b4cf6c519d71..e500c18cbe79 100644
> >> --- a/lib/Kconfig.kasan
> >> +++ b/lib/Kconfig.kasan
> >> @@ -69,6 +69,7 @@ config KASAN_GENERIC
> >>  config KASAN_SW_TAGS
> >>      bool "Software tag-based mode"
> >>      depends on HAVE_ARCH_KASAN_SW_TAGS && CC_HAS_KASAN_SW_TAGS
> >> +    depends on !ARM64_MTE
> >
> > I think that's better as:
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 10cf81d70657..736c32bd8905 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -131,7 +131,7 @@ config ARM64
> >       select HAVE_ARCH_JUMP_LABEL
> >       select HAVE_ARCH_JUMP_LABEL_RELATIVE
> >       select HAVE_ARCH_KASAN if !(ARM64_16K_PAGES && ARM64_VA_BITS_48)
> > -     select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN
> > +     select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN && !ARM64_MTE
> >       select HAVE_ARCH_KGDB
> >       select HAVE_ARCH_MMAP_RND_BITS
> >       select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
> >
>
> I agree with Catalin here, "select HAVE_ARCH_KASAN_SW_TAGS if HAVE_ARCH_KASAN &&
> !ARM64_MTE" should be sufficient.

Sounds good, will do in v2, thanks!