From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH 6/7] media: don't do an unsigned int with a 31 bit shift
Date: Thu, 29 Aug 2019 10:03:09 -0700
Message-ID: <201908291002.2F67F5ADA@keescook>
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To: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Cc: Kate Stewart <kstewart@linuxfoundation.org>, Kamil Debski <kamil@wypas.org>, Hans Verkuil <hverkuil@xs4all.nl>, Andrzej Hajda <a.hajda@samsung.com>, "Lad,
 Prabhakar" <prabhakar.csengg@gmail.com>, Bluecherry Maintainers <maintainers@bluecherrydvr.com>, Krzysztof Kozlowski <krzk@kernel.org>, Sylwester Nawrocki <s.nawrocki@samsung.com>, Nathan Chancellor <natechancellor@gmail.com>, Andrzej Pietrasiewicz <andrzejtp2010@gmail.com>, Anton Sviridenko <anton@corp.bluecherry.net>, Ezequiel Garcia <ezequiel@collabora.com>, Andrey Utkin <andrey.utkin@corp.bluecherry.net>, Antti Palosaari <crope@iki.fi>, Steve Longerbeam <slongerbeam@gmail.com>, Ismael Luceno <ismael@iodev.co.uk>, Linux Media Mailing List <linux-media@vger.kernel.org>, linux-arm-msm@vger.kernel.org, Stanimir Varbanov <stanimir.varbanov@linaro.org>, Jeongtae Park <jtp.park@samsung.com>, linux-samsung-soc@vger.kern
List-Id: linux-samsung-soc@vger.kernel.org

On Thu, Aug 22, 2019 at 04:39:33PM -0300, Mauro Carvalho Chehab wrote:
> Doing something like:
> 
> 	i32 foo = 1, bar;
> 
> 	bar = foo << 31;
> 
> has an undefined behavior in C, as warned by cppcheck, as we're
> shifting a signed integer.
> 
> Instead, force the numbers to be unsigned, in order to solve this
> issue.

I also recommend using the BIT() macro, which does the ULing correctly,
etc.

i.e. instead of:

-	keyup = (gpio & ir->mask_keyup) ? 1 << 31 : 0;
+	keyup = (gpio & ir->mask_keyup) ? 1UL << 31 : 0;

use:

-	keyup = (gpio & ir->mask_keyup) ? 1 << 31 : 0;
+	keyup = (gpio & ir->mask_keyup) ? BIT(31) : 0;

-- 
Kees Cook