Re: [PATCH v3 1/5] mm/kasan: Introduce __kasan_check_{read,write}

[Mark Rutland]

On Wed, Jun 26, 2019 at 04:20:10PM +0200, Marco Elver wrote:
> This introduces __kasan_check_{read,write}. __kasan_check functions may
> be used from anywhere, even compilation units that disable
> instrumentation selectively.
> 
> This change eliminates the need for the __KASAN_INTERNAL definition.
> 
> Signed-off-by: Marco Elver <elver@xxxxxxxxxx>
> Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
> Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
> Cc: Alexander Potapenko <glider@xxxxxxxxxx>
> Cc: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
> Cc: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Pekka Enberg <penberg@xxxxxxxxxx>
> Cc: David Rientjes <rientjes@xxxxxxxxxx>
> Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: kasan-dev@xxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx

Logically this makes sense to me, so FWIW:

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

Thanks,
Mark.

> ---
> v3:
> * Fix Formatting and split introduction of __kasan_check_* and returning
>   bool into 2 patches.
> ---
>  include/linux/kasan-checks.h | 31 ++++++++++++++++++++++++++++---
>  mm/kasan/common.c            | 10 ++++------
>  2 files changed, 32 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h
> index a61dc075e2ce..19a0175d2452 100644
> --- a/include/linux/kasan-checks.h
> +++ b/include/linux/kasan-checks.h
> @@ -2,9 +2,34 @@
>  #ifndef _LINUX_KASAN_CHECKS_H
>  #define _LINUX_KASAN_CHECKS_H
>  
> -#if defined(__SANITIZE_ADDRESS__) || defined(__KASAN_INTERNAL)
> -void kasan_check_read(const volatile void *p, unsigned int size);
> -void kasan_check_write(const volatile void *p, unsigned int size);
> +/*
> + * __kasan_check_*: Always available when KASAN is enabled. This may be used
> + * even in compilation units that selectively disable KASAN, but must use KASAN
> + * to validate access to an address.   Never use these in header files!
> + */
> +#ifdef CONFIG_KASAN
> +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 volatile void *p, unsigned int size)
> +{ }
> +static inline void __kasan_check_write(const volatile void *p, unsigned int size)
> +{ }
> +#endif
> +
> +/*
> + * kasan_check_*: Only available when the particular compilation unit has KASAN
> + * instrumentation enabled. May be used in header files.
> + */
> +#ifdef __SANITIZE_ADDRESS__
> +static inline void kasan_check_read(const volatile void *p, unsigned int size)
> +{
> +	__kasan_check_read(p, size);
> +}
> +static inline void kasan_check_write(const volatile void *p, unsigned int size)
> +{
> +	__kasan_check_read(p, size);
> +}
>  #else
>  static inline void kasan_check_read(const volatile void *p, unsigned int size)
>  { }
> diff --git a/mm/kasan/common.c b/mm/kasan/common.c
> index 242fdc01aaa9..6bada42cc152 100644
> --- a/mm/kasan/common.c
> +++ b/mm/kasan/common.c
> @@ -14,8 +14,6 @@
>   *
>   */
>  
> -#define __KASAN_INTERNAL
> -
>  #include <linux/export.h>
>  #include <linux/interrupt.h>
>  #include <linux/init.h>
> @@ -89,17 +87,17 @@ void kasan_disable_current(void)
>  	current->kasan_depth--;
>  }
>  
> -void kasan_check_read(const volatile 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);
> +EXPORT_SYMBOL(__kasan_check_read);
>  
> -void kasan_check_write(const volatile 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_);
>  }
> -EXPORT_SYMBOL(kasan_check_write);
> +EXPORT_SYMBOL(__kasan_check_write);
>  
>  #undef memset
>  void *memset(void *addr, int c, size_t len)
> -- 
> 2.22.0.410.gd8fdbe21b5-goog
>