Re: [PATCH RFC v2 05/21] kasan: allow VMAP_STACK for HW_TAGS mode

[Dmitry Vyukov]

On Thu, Oct 22, 2020 at 3:19 PM Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
>
> Even though hardware tag-based mode currently doesn't support checking
> vmalloc allocations, it doesn't use shadow memory and works with
> VMAP_STACK as is.
>
> Signed-off-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Link: https://linux-review.googlesource.com/id/I3552cbc12321dec82cd7372676e9372a2eb452ac
> ---
>  arch/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index af14a567b493..3caf7bcdcf93 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -868,7 +868,7 @@ config VMAP_STACK
>         default y
>         bool "Use a virtually-mapped stack"
>         depends on HAVE_ARCH_VMAP_STACK
> -       depends on !KASAN || KASAN_VMALLOC
> +       depends on !(KASAN_GENERIC || KASAN_SW_TAGS) || KASAN_VMALLOC

I find it a bit simpler to interpret:

    depends on !KASAN || KASAN_HW_TAGS || KASAN_VMALLOC

due to simpler structure. But maybe it's just me.

>         help
>           Enable this if you want the use virtually-mapped kernel stacks
>           with guard pages.  This causes kernel stack overflows to be
> --
> 2.29.0.rc1.297.gfa9743e501-goog
>