From: Carlos Martín Nieto <cmn@elego.de>
Date: Wed, 16 Mar 2011 10:41:33 GMT
Subject: Re: [PATCH] valgrind: ignore SSE-based strlen invalid reads
Message-ID: <1300272098.7214.5.camel@bee.lab.cmartin.tk>
In-Reply-To: <20110316095632.GA8277@elie>

On mié, 2011-03-16 at 04:56 -0500, Jonathan Nieder wrote:
> Hi Carlos,
> 
> Carlos Martín Nieto wrote:
> 
> > The C library uses SSE instructions to make strlen (among others)
> > faster, loading 4 bytes at a time and reading past the end of the
> > allocated memory. This read is safe and when the strlen function is
> > inlined, it is (obviously) not replaced by valgrind, which reports a
> > false-possitive.
> 
> It would be GCC rather than the C library if the strlen is inlined, I
> think.  Is this a distinct bug from

 The strlen definition comes from the C library, as far as I know, but
I'll amend to say it's the GNU C Library that's doing weird things.

> <http://bugs.kde.org/show_bug.cgi?id=266961>?  Has it been filed
> with the valgrind maintainers?

 It looks like the same issue, which should also be
https://bugzilla.redhat.com/show_bug.cgi?id=518247 and
http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=590640 which have
patches available. Newer versions of valgrind do not have this "bug".

   cmn