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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20141205193901.GC4963@mwanda>
Date:	Fri, 5 Dec 2014 22:39:01 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
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 05, 2014 at 10:50:19AM -0800, Linus Torvalds wrote:
> 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.
> 

Oh.  Wow...  That's embarrassing.  I thought they were signed for some
reason, and I thought it was weird, but I didn't think about it hard
enough...

I'll redo this.

regards,
dan carpenter
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/