From: Dan Carpenter <dan.carpenter@oracle.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Sasha Levin <sasha.levin@oracle.com>,
Kernel Mailing List <linux-kernel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>
Subject: Re: [RFC 1/2] compiler: use compiler to detect integer overflows
Date: Fri, 5 Dec 2014 22:39:01 +0300 [thread overview]
Message-ID: <20141205193901.GC4963@mwanda> (raw)
In-Reply-To: <CA+55aFxs=mF9vEMh1JN=UpF4UZ9-ojiN==PW8PJNWQ6D18NWFg@mail.gmail.com>
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@oracle.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
prev parent reply other threads:[~2014-12-05 19:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-26 14:00 [RFC 1/2] compiler: use compiler to detect integer overflows Sasha Levin
2014-11-26 14:00 ` [RFC 2/2] kvm: eventfd: detect integer overflow using check_*_overflow Sasha Levin
2014-11-26 17:50 ` Andrey Ryabinin
2014-11-26 17:55 ` Sasha Levin
2014-11-26 18:23 ` Linus Torvalds
2014-11-26 19:06 ` Sasha Levin
2014-11-26 19:12 ` Linus Torvalds
2014-11-26 19:27 ` Sasha Levin
2014-11-26 17:48 ` [RFC 1/2] compiler: use compiler to detect integer overflows Andrey Ryabinin
[not found] ` <CA+55aFzyDC=o_Beg+8hjW8+TQXYWCgQo_yfjgHsTz0LRTiomWA@mail.gmail.com>
2014-11-26 18:50 ` Sasha Levin
2014-11-26 18:58 ` Linus Torvalds
2014-11-27 20:42 ` Dan Carpenter
2014-12-05 9:54 ` Dan Carpenter
2014-12-05 18:50 ` Linus Torvalds
2014-12-05 19:39 ` Dan Carpenter [this message]
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