Re: [PATCH v3 1/3] overflow.h: Add arithmetic shift helper

[Randy Dunlap]

On 07/31/2018 11:09 PM, Kees Cook wrote:
> From: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> 
> Add shift_overflow() helper to assist driver authors in ensuring that
> shift operations don't cause overflows or other odd conditions.
> 
> Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxxxx>
> Signed-off-by: Leon Romanovsky <leonro@xxxxxxxxxxxx>
> [kees: tweaked comments and commit log, dropped unneeded assignment]
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> ---
>  include/linux/overflow.h | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> index 8712ff70995f..69fc366ce865 100644
> --- a/include/linux/overflow.h
> +++ b/include/linux/overflow.h
> @@ -202,6 +202,37 @@
>  
>  #endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */
>  
> +/** check_shift_overflow() - Calculate a left-shifted value and check overflow
> + *
> + * @a: Value to be shifted
> + * @b: How many bits left to shift
> + * @d: Pointer to where to store the result
> + *
> + * Computes *@d = (@a << @s)
> + *

missed                     @b [again]


-- 
~Randy