This is the mail archive of the
libc-alpha@sourceware.org
mailing list for the glibc project.
Re: [PATCH] Adjust pointers to triplets in netgroup query data (BZ #16474)
- From: OndÅej BÃlka <neleai at seznam dot cz>
- To: Andreas Schwab <schwab at linux-m68k dot org>
- Cc: Siddhesh Poyarekar <siddhesh at redhat dot com>, libc-alpha at sourceware dot org
- Date: Fri, 24 Jan 2014 16:37:27 +0100
- Subject: Re: [PATCH] Adjust pointers to triplets in netgroup query data (BZ #16474)
- Authentication-results: sourceware.org; auth=none
- References: <20140121172451 dot GJ5544 at spoyarek dot pnq dot redhat dot com> <20140123123841 dot GA5631 at domone dot podge> <20140124085757 dot GA5544 at spoyarek dot pnq dot redhat dot com> <87d2jhtnl8 dot fsf at igel dot home>
On Fri, Jan 24, 2014 at 04:18:43PM +0100, Andreas Schwab wrote:
> Siddhesh Poyarekar <siddhesh@redhat.com> writes:
>
> > @@ -241,7 +241,17 @@ addgetnetgrentX (struct database_dyn *db, int fd, request_header *req,
> > if (buflen - req->key_len - bufused < needed)
> > {
> > buflen += MAX (buflen, 2 * needed);
> > - buffer = xrealloc (buffer, buflen);
> > + char *newbuf = xrealloc (buffer, buflen);
> > + /* Adjust the pointers in the new
> > + buffer. */
> > + nhost = (nhost ? newbuf + (nhost - buffer)
>
> This is undefined. If realloc was sucessful then buffer is no longer
> valid. You need to compute nhost - buffer before doing the realloc.
>
As these are not referenced it leads to equivalent code. Only problem with that code
would be static analyzer flagging this as false positive.