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

[Andrew Pinski]

On Mon, Oct 21, 2024 at 10:21 AM Will Deacon <will@xxxxxxxxxx> wrote:
>
> 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?

Yes, tested from GCC 11+, kernel-hwaddress was added in GCC 11.
Also tested from clang 9.0+ and it works there too.

Thanks,
Andrew Pinski

>
> Will