[PATCH v17 03/15] arm64: Introduce prctl() options to control the tagged user addresses ABI

[Kees Cook]

On Thu, Jun 13, 2019 at 04:26:32PM +0100, Catalin Marinas wrote:
> On Thu, Jun 13, 2019 at 12:02:35PM +0100, Dave P Martin wrote:
> > On Wed, Jun 12, 2019 at 01:43:20PM +0200, Andrey Konovalov wrote:
> > > +static int zero;
> > > +static int one = 1;
> > 
> > !!!
> > 
> > And these can't even be const without a cast.  Yuk.
> > 
> > (Not your fault though, but it would be nice to have a proc_dobool() to
> > avoid this.)
> 
> I had the same reaction. Maybe for another patch sanitising this pattern
> across the kernel.

That's actually already happening (via -mm tree last I looked). tl;dr:
it ends up using a cast hidden in a macro. It's in linux-next already
along with a checkpatch.pl addition to yell about doing what's being
done here. ;)

https://lore.kernel.org/lkml/20190430180111.10688-1-mcroce@redhat.com/#r

-- 
Kees Cook