Re: [PATCH] overflow.h: Rename __ab_c_size() to __calc_size()

[Borislav Petkov]

On Fri, Apr 05, 2019 at 10:09:31AM +0200, Rasmus Villemoes wrote:
> On 05/04/2019 09.52, Borislav Petkov wrote:
> > On Fri, Apr 05, 2019 at 08:26:45AM +0200, Rasmus Villemoes wrote:
> 
> >> It computes a*b+c with overflow checking at each step. calc_size
> >> is way too generic and doesn't say anything at all about how the
> >> calc(ulation) is done.
> > 
> > Ok, whatever.
> > 
> > Then it would need at least a comment above it to state what it does. I
> > don't want to go and parse the macros each time.
> 
> It's an internal helper, and struct_size is fully kernel-doc'ed. But
> yeah, a comment wouldn't hurt, and let's rename the parameters so they
> match the abc naming.
> 
> diff --git a/include/linux/overflow.h b/include/linux/overflow.h
> index 40b48e2133cb..6534a727cadb 100644
> --- a/include/linux/overflow.h
> +++ b/include/linux/overflow.h
> @@ -278,11 +278,15 @@ static inline __must_check size_t
> array3_size(size_t a, size_t b, size_t c)
>         return bytes;
>  }
> 
> -static inline __must_check size_t __ab_c_size(size_t n, size_t size,
> size_t c)
> +/*
> + * Compute a*b+c, returning SIZE_MAX on overflow. Internal helper for
> + * struct_size() below.
> + */
> +static inline __must_check size_t __ab_c_size(size_t a, size_t b, size_t c)
>  {
>         size_t bytes;
> 
> -       if (check_mul_overflow(n, size, &bytes))
> +       if (check_mul_overflow(a, b, &bytes))
>                 return SIZE_MAX;
>         if (check_add_overflow(bytes, c, &bytes))
>                 return SIZE_MAX;
> 
>

Reported-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Borislav Petkov <bp@xxxxxxx>

Thx.

-- 
Regards/Gruss,
    Boris.

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