Re: [PATCH v3 3/3] kasan: add memory corruption identification support for hardware tag-based mode

From: Andrey Konovalov
Date: Tue Jun 22 2021 - 09:55:15 EST


On Sun, Jun 20, 2021 at 2:48 PM Kuan-Ying Lee
<Kuan-Ying.Lee@xxxxxxxxxxxx> wrote:
>
> Add memory corruption identification support for hardware tag-based
> mode. We store one old free pointer tag and free backtrace.

Please explain why only one.

> Signed-off-by: Kuan-Ying Lee <Kuan-Ying.Lee@xxxxxxxxxxxx>
> Suggested-by: Marco Elver <elver@xxxxxxxxxx>
> Cc: Andrey Ryabinin <ryabinin.a.a@xxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> lib/Kconfig.kasan | 2 +-
> mm/kasan/kasan.h | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan
> index 6f5d48832139..2cc25792bc2f 100644
> --- a/lib/Kconfig.kasan
> +++ b/lib/Kconfig.kasan
> @@ -157,7 +157,7 @@ config KASAN_STACK
>
> config KASAN_TAGS_IDENTIFY
> bool "Enable memory corruption identification"
> - depends on KASAN_SW_TAGS
> + depends on KASAN_SW_TAGS || KASAN_HW_TAGS
> help
> This option enables best-effort identification of bug type
> (use-after-free or out-of-bounds) at the cost of increased
> diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h
> index b0fc9a1eb7e3..d6f982b8a84e 100644
> --- a/mm/kasan/kasan.h
> +++ b/mm/kasan/kasan.h
> @@ -153,7 +153,7 @@ struct kasan_track {
> depot_stack_handle_t stack;
> };
>
> -#ifdef CONFIG_KASAN_TAGS_IDENTIFY
> +#if defined(CONFIG_KASAN_TAGS_IDENTIFY) && defined(CONFIG_KASAN_SW_TAGS)
> #define KASAN_NR_FREE_STACKS 5
> #else
> #define KASAN_NR_FREE_STACKS 1
> --
> 2.18.0
>

Other than that:

Reviewed-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>