Re: [PATCH] randomize_range: use random long instead of int

[Kees Cook]

On Mon, Jul 25, 2016 at 11:25 AM,  <william.c.roberts@xxxxxxxxx> wrote:
> From: William Roberts <william.c.roberts@xxxxxxxxx>
>
> Use a long when generating the random range rather than
> an int. This will produce better random distributions as
> well as matching all the types at hand.
>
> Signed-off-by: William Roberts <william.c.roberts@xxxxxxxxx>

I agree, this is what I pointed out back in Feb:
https://lkml.org/lkml/2016/2/4/854

Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>

Andrew, can you pick this up for 4.8?

-Kees

> ---
>  drivers/char/random.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index 0158d3b..bbf11b5 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1837,7 +1837,8 @@ randomize_range(unsigned long start, unsigned long end, unsigned long len)
>
>         if (end <= start + len)
>                 return 0;
> -       return PAGE_ALIGN(get_random_int() % range + start);
> +
> +       return PAGE_ALIGN(get_random_long() % range + start);
>  }
>
>  /* Interface for in-kernel drivers of true hardware RNGs.
> --
> 1.9.1
>



-- 
Kees Cook
Chrome OS & Brillo Security