From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Kees Cook <keescook@chromium.org>
Cc: Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
Marco Elver <elver@google.com>,
Eric Biggers <ebiggers@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
"Gustavo A. R. Silva" <gustavoars@kernel.org>,
linux-hardening@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 3/3] overflow: Introduce wrapping_inc() and wrapping_dec()
Date: Wed, 7 Feb 2024 18:34:07 +0200 [thread overview]
Message-ID: <ZcOw_5-1ghxJrqfg@smile.fi.intel.com> (raw)
In-Reply-To: <202402070806.445F7F7F03@keescook>
On Wed, Feb 07, 2024 at 08:08:14AM -0800, Kees Cook wrote:
> On Wed, Feb 07, 2024 at 05:31:54PM +0200, Andy Shevchenko wrote:
> > On Wed, Feb 7, 2024 at 5:24 PM Kees Cook <keescook@chromium.org> wrote:
> > >
> > > This allows replacements of the idioms "var += offset" and "var -= offset"
> > > with the wrapping_inc() and wrapping_dec() helpers respectively. They
> > > will avoid wrap-around sanitizer instrumentation.
> > >
> > > Add to the selftests to validate behavior and lack of side-effects.
> >
> > I would expect inc/dec to add/subtract 1. So, to me the terminology is
> > confusing. The list of the C/C++ operators on Wikipedia describes
> > above as
> >
> > += Assignment by sum
> > -= Assignment by difference
> >
> > Hence the proposal is to have
> >
> > wrapping_sum()
> > wrapping_diff()
>
> I think maybe the missing phrase is "assign", which is what makes
> argument 1 "special" -- it's being changed. Perhaps:
>
> wrapping_add_assign()
> wrapping_sub_assign()
>
> ?
WFM!
--
With Best Regards,
Andy Shevchenko
prev parent reply other threads:[~2024-02-07 16:34 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-02-07 15:24 [PATCH v5 0/3] overflow: Introduce wrapping helpers Kees Cook
2024-02-07 15:24 ` [PATCH v5 1/3] overflow: Adjust check_*_overflow() kern-doc to reflect results Kees Cook
2024-02-07 15:24 ` [PATCH v5 2/3] overflow: Introduce wrapping_add(), wrapping_sub(), and wrapping_mul() Kees Cook
2024-02-07 18:06 ` Marco Elver
2024-02-07 15:24 ` [PATCH v5 3/3] overflow: Introduce wrapping_inc() and wrapping_dec() Kees Cook
2024-02-07 15:31 ` Andy Shevchenko
2024-02-07 16:08 ` Kees Cook
2024-02-07 16:34 ` Andy Shevchenko [this message]
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