From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S936166AbXGTBbU@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S936166AbXGTBbU (ORCPT <rfc822;w@1wt.eu>);
	Thu, 19 Jul 2007 21:31:20 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761107AbXGTBbM
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Thu, 19 Jul 2007 21:31:12 -0400
Received: from smtp2.linux-foundation.org ([207.189.120.14]:52176 "EHLO
	smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1759851AbXGTBbK (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 19 Jul 2007 21:31:10 -0400
Date: Thu, 19 Jul 2007 18:29:52 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: linux-kernel@vger.kernel.org, Paul Mundt <lethal@linux-sh.org>,
       Tom Zanussi <zanussi@us.ibm.com>, Karim Yaghmour <karim@opersys.com>,
       Jesper Juhl <jesper.juhl@gmail.com>,
       "David J. Wilder" <wilder@us.ibm.com>
Subject: Re: [PATCH] Fix a use after free bug in kernel->userspace relay
 file support
Message-Id: <20070719182952.5f437e64.akpm@linux-foundation.org>
In-Reply-To: <20070720010909.GA4298@Krystal>
References: <20070720010909.GA4298@Krystal>
X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
X-Mailing-List: linux-kernel@vger.kernel.org

On Thu, 19 Jul 2007 21:09:09 -0400
Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> Coverity spotted what looks like a real possible case of using a 
> variable after it has been freed.
> The problem is in kernel/relay.c::relay_open_buf()
> 
> If the code hits "goto free_buf;" it ends up in this code :
> 
>   free_buf:
>     	relay_destroy_buf(buf);	<--- calls kfree() on 'buf'.
>   free_name:
>    	kfree(tmpname);
>   end:
>   	return buf;		<-- use after free of 'buf'.
> 
> I read through the callers and they all handle a NULL return 
> from this function as an error (and hitting the 'free_buf' label 
> only happens on failure to chan->cb->create_buf_file(), so that 
> looks like a clear error to me). 
> 
> The patch simply sets 'buf' to NULL after the call to 
> relay_destroy_buf(buf); - as far as I can see that should take 
> care of the problem.
> 
> The patch also corrects a reference to a documentation file while 
> I was at it.
> 
> Note from Mathieu: the documentation reference change should have been
> done in a separate patch, but I guess no one will really care.
> 
> Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
> Acked-by: "David J. Wilder" <wilder@us.ibm.com>
> Tested-by: "David J. Wilder" <wilder@us.ibm.com>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

I'm going to infer from all this that the patch was actually written
by Jesper.  Correct?

If so, it shuld have had From: Jesper Juhl <jesper.juhl@gmail.com>
right at the start of the changelog.