Re: [PATCH v1 1/2] overflow: Allow to sum a few arguments at once

[Kees Cook <kees@kernel.org>]

On Fri, Jun 19, 2026 at 09:45:18AM +0300, Andy Shevchenko wrote:
> On Thu, Jun 18, 2026 at 08:47:34PM -0700, Kees Cook wrote:
> > On Wed, Jun 17, 2026 at 01:12:36PM +0200, Andy Shevchenko wrote:
> > > Convert size_add() to take variadic argument, so we can simplify users
> > > with using a macro only once.
> > 
> > Oh, this is fun. I like it. :)
> 
> He-he :-)
> 
> ...
> 
> > > +#define __size_add4(addend1, addend2, addend3, addend4, addend5, ...)		\
> > > +	__size_add(__size_add3(addend1,  addend2, addend3, addend4), addend5)
> > 
> > Is 4 the max seen in practice?
> 
> In patch 2 there are 5! In cover letter I also mentioned a new user
> (there are actually three). And I remember seeing 3 somewhere else.

I feel like we should allow size_mul() to work this way too, though I
don't find any users that would need it, so I guess just size_add()?

I'm fine for this to go via whatever tree is first to use it:

Acked-by: Kees Cook <kees@kernel.org>


-- 
Kees Cook