Re: [PATCH 3/4] mm/kasan: add API to check memory regions

[Alexander Potapenko]

On Fri, May 6, 2016 at 2:45 PM, Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:
> Memory access coded in an assembly won't be seen by KASAN as a compiler
> can instrument only C code. Add kasan_check_[read,write]() API
> which is going to be used to check a certain memory range.
>
> Signed-off-by: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> ---
>  MAINTAINERS                  |  2 +-
>  include/linux/kasan-checks.h | 12 ++++++++++++
>  mm/kasan/kasan.c             | 12 ++++++++++++
>  3 files changed, 25 insertions(+), 1 deletion(-)
>  create mode 100644 include/linux/kasan-checks.h
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 43b85c1..3a9471c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6363,7 +6363,7 @@ S:        Maintained
>  F:     arch/*/include/asm/kasan.h
>  F:     arch/*/mm/kasan_init*
>  F:     Documentation/kasan.txt
> -F:     include/linux/kasan.h
> +F:     include/linux/kasan*.h
>  F:     lib/test_kasan.c
>  F:     mm/kasan/
>  F:     scripts/Makefile.kasan
> diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> new file mode 100644
> index 0000000..b7f8ace
> --- /dev/null
> +++ b/include/linux/kasan-checks.h
> @@ -0,0 +1,12 @@
> +#ifndef _LINUX_KASAN_CHECKS_H
> +#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);
> +#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) { }
> +#endif
> +
> +#endif
> diff --git a/mm/kasan/kasan.c b/mm/kasan/kasan.c
> index 6e4072c..54f0ea7 100644
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -299,6 +299,18 @@ 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)
> +{
> +       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)
> +{
> +       check_memory_region((unsigned long)p, size, true, _RET_IP_);
> +}
> +EXPORT_SYMBOL(kasan_check_write);
> +
>  #undef memset
>  void *memset(void *addr, int c, size_t len)
>  {
> --
> 2.7.3
>
Acked-by: Alexander Potapenko <glider@xxxxxxxxxx>


-- 
Alexander Potapenko
Software Engineer

Google Germany GmbH
Erika-Mann-StraÃe, 33
80636 MÃnchen

GeschÃftsfÃhrer: Matthew Scott Sucherman, Paul Terence Manicle
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg