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Date:   Thu, 13 Jun 2019 22:13:54 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Catalin Marinas <catalin.marinas@arm.com>
Cc:     Dave Martin <Dave.Martin@arm.com>,
        Andrey Konovalov <andreyknvl@google.com>,
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        Mark Rutland <mark.rutland@arm.com>,
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        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Subject: Re: [PATCH v17 03/15] arm64: Introduce prctl() options to control
 the tagged user addresses ABI
Message-ID: <201906132209.FC65A3C771@keescook>
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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