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Re: Cwd.xs: off-by-one buffer overflow in realpath()

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From:
H.Merijn Brand
Date:
November 3, 2003 13:39
Subject:
Re: Cwd.xs: off-by-one buffer overflow in realpath()
Message ID:
20031103223849.9AE1.H.M.BRAND@hccnet.nl
On Mon 03 Nov 2003 22:35, Rafael Garcia-Suarez <rgarciasuarez@free.fr> wrote:
> H.Merijn Brand wrote:
> > On Mon 03 Nov 2003 22:24, Rafael Garcia-Suarez <rgarciasuarez@free.fr> wrote:
> > > Casey West wrote:
> > > > ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-03:08.realpath.asc 
> > > 
> > > Thanks, applied as #21646 to blead. (by hand, for some reason.)
> > > 
> > > > --- perl-current-orig/ext/Cwd/Cwd.xs    Thu May 16 18:16:19 2002
> > > > +++ perl-current/ext/Cwd/Cwd.xs Thu Oct 30 12:08:12 2003
> > > > @@ -166,7 +166,7 @@
> > > >                 rootd = 0;
> > > >  
> > > >         if (*wbuf) {
> > > > -               if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
> > > > +               if (strlen(resolved) + strlen(wbuf) + (1-rootd) + 1 > MAXPATHLEN) {
> > 
> > This correct? 1 *-* rootd
> > This is completely different from off-by-one, as the subject says
> 
> Looks correct to me. rootd is 0 or 1 depending on whether the path
> represents the root directory ("/\0") or not.

So the patch *reverses* rootd.

Would rootd^1 not be more obvious then? Or am I just nitpicking

-- 
H.Merijn Brand        Amsterdam Perl Mongers (http://amsterdam.pm.org/)
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   AIX 4.3, SuSE 8.2, and Win2k.           http://www.cmve.net/~merijn/
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