linux-kernel - Re: [RFC 1/2] compiler: use compiler to detect integer overflows

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Message-ID: <CA+55aFxs=mF9vEMh1JN=UpF4UZ9-ojiN==PW8PJNWQ6D18NWFg@mail.gmail.com>
Date:	Fri, 5 Dec 2014 10:50:19 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Dan Carpenter <dan.carpenter@...cle.com>
Cc:	Sasha Levin <sasha.levin@...cle.com>,
	Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ingo Molnar <mingo@...nel.org>
Subject: Re: [RFC 1/2] compiler: use compiler to detect integer overflows

On Fri, Dec 5, 2014 at 1:54 AM, Dan Carpenter <dan.carpenter@...cle.com> wrote:
>
> There are some false positives which do:
>
>         if ((u16)(u16_foo + u16_bar) < u16_foo) {

Actually, the worse false positive is the ones that are pointer comparisons.

A compiler that does those as signed is just broken. It's happened,
but it's *still* completely broken.

                  Linus
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