Re: [PATCH v4 5/7] kasan: allow kasan_check_read/write() to accept pointers to volatiles

Mark Rutland
2017-06-19T10:50:59Z

On Sat, Jun 17, 2017 at 11:15:31AM +0200, Dmitry Vyukov wrote:
> Currently kasan_check_read/write() accept 'const void*', make them
> accept 'const volatile void*'. This is required for instrumentation
> of atomic operations and there is just no reason to not allow that.
>
> Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-kernel@vger.kernel.org
> Cc: x86@kernel.org
> Cc: linux-mm@kvack.org
> Cc: kasan-dev@googlegroups.com

Looks sane to me, and I can confirm this doesn't advervsely affect
arm64. FWIW:

Acked-by: Mark Rutland <mark.rutland@arm.com>

Mark.

> ---
> include/linux/kasan-checks.h | 10 ++++++----
> mm/kasan/kasan.c | 4 ++--
> 2 files changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> index b7f8aced7870..41960fecf783 100644
> --- a/include/linux/kasan-checks.h
> +++ b/include/linux/kasan-checks.h
> @@ -2,11 +2,13 @@
> #define _LINUX_KASAN_CHECKS_H
>
> #ifdef CONFIG_KASAN
> -void kasan_check_read(const void *p, unsigned int size);
> -void kasan_check_write(const void *p, unsigned int size);
> +void kasan_check_read(const volatile void *p, unsigned int size);
> +void kasan_check_write(const volatile void *p, unsigned int size);
> #else
> -static inline void kasan_check_read(const void *p, unsigned int size) { }
> -static inline void kasan_check_write(const void *p, unsigned int size) { }
> +static inline void kasan_check_read(const volatile void *p, unsigned int size)
> +{ }
> +static inline void kasan_check_write(const volatile void *p, unsigned int size)
> +{ }
> #endif
>
> #endif
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index c81549d5c833..edacd161c0e5 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -333,13 +333,13 @@ static void check_memory_region(unsigned long addr,
> check_memory_region_inline(addr, size, write, ret_ip);
> }
>
> -void kasan_check_read(const void *p, unsigned int size)
> +void kasan_check_read(const volatile void *p, unsigned int size)
> {
> check_memory_region((unsigned long)p, size, false, _RET_IP_);
> }
> EXPORT_SYMBOL(kasan_check_read);
>
> -void kasan_check_write(const void *p, unsigned int size)
> +void kasan_check_write(const volatile void *p, unsigned int size)
> {
> check_memory_region((unsigned long)p, size, true, _RET_IP_);
> }
> --
> 2.13.1.518.g3df882009-goog
>