Re: [PATCH 1/2] kasan: Fix Software Tag-Based KASAN with GCC

[Will Deacon]

On Mon, Oct 21, 2024 at 02:00:10PM +0200, Marco Elver wrote:
> Per [1], -fsanitize=kernel-hwaddress with GCC currently does not disable
> instrumentation in functions with __attribute__((no_sanitize_address)).
> 
> However, __attribute__((no_sanitize("hwaddress"))) does correctly
> disable instrumentation. Use it instead.
> 
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117196 [1]
> Link: https://lore.kernel.org/r/000000000000f362e80620e27859@xxxxxxxxxx
> Link: https://lore.kernel.org/r/ZvFGwKfoC4yVjN_X@J2N7QTR9R3
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218854
> Reported-by: syzbot+908886656a02769af987@xxxxxxxxxxxxxxxxxxxxxxxxx
> Tested-by: Andrey Konovalov <andreyknvl@xxxxxxxxx>
> Cc: Andrew Pinski <pinskia@xxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> ---
>  include/linux/compiler-gcc.h | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
> index f805adaa316e..cd6f9aae311f 100644
> --- a/include/linux/compiler-gcc.h
> +++ b/include/linux/compiler-gcc.h
> @@ -80,7 +80,11 @@
>  #define __noscs __attribute__((__no_sanitize__("shadow-call-stack")))
>  #endif
>  
> +#ifdef __SANITIZE_HWADDRESS__
> +#define __no_sanitize_address __attribute__((__no_sanitize__("hwaddress")))
> +#else
>  #define __no_sanitize_address __attribute__((__no_sanitize_address__))
> +#endif

Does this work correctly for all versions of GCC that support
-fsanitize=kernel-hwaddress?

Will