Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Wed, 5 Aug 2020 13:50:24 -0700
From:   Kees Cook <keescook@chromium.org>
To:     Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc:     Jason Gunthorpe <jgg@ziepe.ca>, Leon Romanovsky <leon@kernel.org>,
        "Gustavo A. R. Silva" <gustavoars@kernel.org>,
        Matthew Wilcox <willy@infradead.org>,
        linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com,
        Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [RFC] saturate check_*_overflow() output?
Message-ID: <202008051349.553E49E12@keescook>
References: <202008031118.36756FAD04@keescook>
 <f177a821-74a3-e868-81d3-55accfb5b161@rasmusvillemoes.dk>
 <202008041137.02D231B@keescook>
 <6d190601-68f1-c086-97ac-2ee1c08f5a34@rasmusvillemoes.dk>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <6d190601-68f1-c086-97ac-2ee1c08f5a34@rasmusvillemoes.dk>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Wed, Aug 05, 2020 at 01:38:58PM +0200, Rasmus Villemoes wrote:
> Anyway, we don't need to apply it to the last expression inside ({}), we
> can just pass the whole ({}) to must_check_overflow() as in
> 
> -#define check_sub_overflow(a, b, d) ({         \
> +#define check_sub_overflow(a, b, d) must_check_overflow(({             \

Oh! Yes, of course. I was blinded by looking inside the macro and not
wanting to spoil the type magic. Yes, that's perfect. I will spin a
patch...

-- 
Kees Cook