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Date:   Sun, 11 Sep 2022 12:31:21 +0200
From:   Andi Shyti <andi.shyti@linux.intel.com>
To:     Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc:     intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        dri-devel@lists.freedesktop.org, mchehab@kernel.org,
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        thomas.hellstrom@linux.intel.com, jani.nikula@intel.com,
        nirmoy.das@intel.com, airlied@redhat.com, daniel@ffwll.ch,
        andi.shyti@linux.intel.com, andrzej.hajda@intel.com,
        keescook@chromium.org, mauro.chehab@linux.intel.com,
        linux@rasmusvillemoes.dk, vitor@massaru.org, dlatypov@google.com,
        ndesaulniers@google.com
Subject: Re: [PATCH v10 1/9] overflow: Allow mixed type arguments
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References: <20220909105913.752049-1-gwan-gyeong.mun@intel.com>
 <20220909105913.752049-2-gwan-gyeong.mun@intel.com>
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Hi Kees,

On Fri, Sep 09, 2022 at 07:59:05PM +0900, Gwan-gyeong Mun wrote:
> From: Kees Cook <keescook@chromium.org>
> 
> When the check_[op]_overflow() helpers were introduced, all arguments were
> required to be the same type to make the fallback macros simpler. However,
> now that the fallback macros have been removed[1], it is fine to allow
> mixed types, which makes using the helpers much more useful, as they
> can be used to test for type-based overflows (e.g. adding two large ints
> but storing into a u8), as would be handy in the drm core[2].
> 
> Remove the restriction, and add additional self-tests that exercise some
> of the mixed-type overflow cases, and double-check for accidental macro
> side-effects.

I would split in two different patches the check_[op]_overflow()
helpers with the tests.

Overall they look good though.

> [1] https://git.kernel.org/linus/4eb6bd55cfb22ffc20652732340c4962f3ac9a91
> [2] https://lore.kernel.org/lkml/20220824084514.2261614-2-gwan-gyeong.mun@intel.com
> 
> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
> Cc: Andrzej Hajda <andrzej.hajda@intel.com>
> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: linux-hardening@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Gwan-gyeong, can you please add your SoB here? And you don't need
to 'Cc:' yourself.

Andi