linux-kernel - Re: [PATCH v10 2/9] overflow: Move and add few utility macros into overflow

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Date:   Tue, 13 Sep 2022 04:53:32 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>
Cc:     intel-gfx@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, mchehab@...nel.org,
        chris@...is-wilson.co.uk, matthew.auld@...el.com,
        thomas.hellstrom@...ux.intel.com, jani.nikula@...el.com,
        nirmoy.das@...el.com, airlied@...hat.com, daniel@...ll.ch,
        andi.shyti@...ux.intel.com, andrzej.hajda@...el.com,
        mauro.chehab@...ux.intel.com, linux@...musvillemoes.dk,
        vitor@...saru.org, dlatypov@...gle.com, ndesaulniers@...gle.com
Subject: Re: [PATCH v10 2/9] overflow: Move and add few utility macros into
 overflow

On Fri, Sep 09, 2022 at 07:59:06PM +0900, Gwan-gyeong Mun wrote:
> It moves overflows_type utility macro into overflow header from i915_utils
> header. The overflows_type can be used to catch the truncaion (overflow)
> between different data types. And it adds check_assign() macro which
> performs an assigning source value into destination pointer along with an
> overflow check. overflow_type macro has been improved to handle the
> different data types between source and destination by check_add_overflow
> macro. It also adds check_assign_user_ptr macro which performs an assigning
> source value into destination pointer type variable along with an overflow
> check. If an explicit overflow check is required while assigning,
> check_assign_user_ptr() can be used to assign integers into pointers along
> with an overflow check.
> 
> v3: Add is_type_unsigned() macro (Mauro)
>     Modify overflows_type() macro to consider signed data types (Mauro)
>     Fix the problem that safe_conversion() macro always returns true
> v4: Fix kernel-doc markups
> v6: Move macro addition location so that it can be used by other than drm
>     subsystem (Jani, Mauro, Andi)
>     Change is_type_unsigned to is_unsigned_type to have the same name form
>     as is_signed_type macro
> v8: Add check_assign() and remove safe_conversion() (Kees)
>     Fix overflows_type() to use gcc's built-in overflow function (Andrzej)
>     Add overflows_ptr() to allow overflow checking when assigning a value
>     into a pointer variable (G.G.)
> v9: Fix overflows_type() to use __builtin_add_overflow() instead of
>     __builtin_add_overflow_p() (Andrzej)
>     Fix overflows_ptr() to use overflows_type() with the unsigned long type
>     (Andrzej)
> v10: Remove a redundant type checking for a pointer. (Andrzej)
>      Use updated check_add_overflow macro instead of __builtin_add_overflow
>      (G.G)
>      Add check_assign_user_ptr() macro and drop overflows_ptr() macro(Kees)
> 
> Signed-off-by: Gwan-gyeong Mun <gwan-gyeong.mun@...el.com>

Acked-by: Kees Cook <keescook@...omium.org>

-- 
Kees Cook