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Date: Mon, 05 Feb 2024 23:21:41 +0000
From: Kees Cook <kees@kernel.org>
To: Eric Biggers <ebiggers@kernel.org>, Kees Cook <keescook@chromium.org>
CC: linux-hardening@vger.kernel.org,
 Rasmus Villemoes <rasmus.villemoes@prevas.dk>,
 Mark Rutland <mark.rutland@arm.com>,
 "Gustavo A. R. Silva" <gustavoars@kernel.org>,
 Marco Elver <elver@google.com>, linux-kernel@vger.kernel.org
Subject: =?US-ASCII?Q?Re=3A_=5BPATCH_v3_2/3=5D_overflow=3A_Introduce?= =?US-ASCII?Q?_add=5Fwrap=28=29=2C_sub=5Fwr?= =?US-ASCII?Q?ap=28=29=2C_and_mul=5Fwrap=28=29?=
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On February 5, 2024 11:17:12 PM GMT, Eric Biggers <ebiggers@kernel=2Eorg> =
wrote:
>On Mon, Feb 05, 2024 at 02:44:14PM -0800, Kees Cook wrote:
>> On Mon, Feb 05, 2024 at 12:21:45PM -0800, Eric Biggers wrote:
>> > On Mon, Feb 05, 2024 at 01:12:30AM -0800, Kees Cook wrote:
>> > > Subject: Re: [PATCH v3 2/3] overflow: Introduce add_wrap(), sub_wra=
p(), and mul_wrap()
>> >=20
>> > Maybe these should be called wrapping_add, wrapping_sub, and wrapping=
_mul?
>> > Those names are more grammatically correct, and Rust chose those name=
s too=2E
>>=20
>> Sure, that works for me=2E What bout the inc_wrap() and dec_wrap() name=
s?
>> I assume wrapping_inc() and wrapping_dec() ?
>>=20
>
>Yes, though I'm not sure those should exist at all=2E  Maybe a +=3D b sho=
uld just
>become a =3D wrapping_add(a, b), instead of wrapping_inc(a, b)?
>wrapping_inc(a, b) isn't as self-explanatory=2E  Likewise for wrapping_de=
c=2E

It was to avoid repeating type information, as it would go from:

var_a +=3D var_b;

to:

var_a =3D wrapping_add(typeof(var_a), var_a, var_b);

Which repeats "var_a" 3 times=2E :|


--=20
Kees Cook