overflow: Implement size_t saturating arithmetic helpers [LWN.net]

From:		Kees Cook <keescook-AT-chromium.org>
To:		Rasmus Villemoes <linux-AT-rasmusvillemoes.dk>
Subject:		[PATCH 0/2] overflow: Implement size_t saturating arithmetic helpers
Date:		Mon, 20 Sep 2021 11:08:51 -0700
Message-ID:		<20210920180853.1825195-1-keescook@chromium.org>
Cc:		Kees Cook <keescook-AT-chromium.org>, "Gustavo A. R. Silva" <gustavoars-AT-kernel.org>, Nathan Chancellor <nathan-AT-kernel.org>, Jason Gunthorpe <jgg-AT-ziepe.ca>, Nick Desaulniers <ndesaulniers-AT-google.com>, Leon Romanovsky <leon-AT-kernel.org>, Keith Busch <kbusch-AT-kernel.org>, Len Baker <len.baker-AT-gmx.com>, linux-kernel-AT-vger.kernel.org, linux-hardening-AT-vger.kernel.org
Archive-link:		Article

Hi,

While doing more array_size() scans on the kernel, and reviewing recent
struct_size() work[1], it became clear we needed helpers to perform
composed saturating add and multiplies. This creates those helpers and
updates the self tests to check them.

Thanks,

-Kees

[1] https://lore.kernel.org/lkml/?q=%22open-coded+arithmetic%22

Kees Cook (2):
  overflow: Implement size_t saturating arithmetic helpers
  test_overflow: Regularize test reporting output

 include/linux/overflow.h | 140 ++++++++++++++++++++++++---------------
 lib/test_overflow.c      | 111 ++++++++++++++++++++++++-------
 2 files changed, 175 insertions(+), 76 deletions(-)

-- 
2.30.2