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

[Dave Martin]

On Thu, Jun 13, 2019 at 10:13:54PM -0700, Kees Cook wrote:
> 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

Hmmm, that is marginally less bad.

Ideally we'd have a union in there, not just a bunch of void *.  I may
look at that someday...

Cheers
---Dave