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

Dmitry Vyukov
2017-06-19T13:11:44Z

On Mon, Jun 19, 2017 at 12:50 PM, Mark Rutland <mark.rutland@arm.com> wrote:
> 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.

Great! Thanks for testing.

Ingo, what are your thoughts? Are you taking this to locking tree? When?

>> ---
>> 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
>>