From owner-freebsd-hackers@FreeBSD.ORG  Sat Feb 21 10:16:41 2004
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id B282716A4CE; Sat, 21 Feb 2004 10:16:41 -0800 (PST)
Received: from fledge.watson.org (fledge.watson.org [204.156.12.50])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 5D2A543D1F; Sat, 21 Feb 2004 10:16:41 -0800 (PST)
	(envelope-from robert@fledge.watson.org)
Received: from fledge.watson.org (localhost [127.0.0.1])
	by fledge.watson.org (8.12.10/8.12.10) with ESMTP id i1LIFtDL072587;
	Sat, 21 Feb 2004 13:15:55 -0500 (EST)
	(envelope-from robert@fledge.watson.org)
Received: from localhost (robert@localhost)i1LIFtW1072584;
	Sat, 21 Feb 2004 13:15:55 -0500 (EST)
	(envelope-from robert@fledge.watson.org)
Date: Sat, 21 Feb 2004 13:15:55 -0500 (EST)
From: Robert Watson <rwatson@FreeBSD.org>
X-Sender: robert@fledge.watson.org
To: John Baldwin <jhb@FreeBSD.org>
In-Reply-To: <200402201340.23218.jhb@FreeBSD.org>
Message-ID: <Pine.NEB.3.96L.1040221131348.70781V-100000@fledge.watson.org>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: hackers@FreeBSD.org
cc: Ted Unangst <tedu@coverity.com>
Subject: Re: use after free bugs
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 21 Feb 2004 18:16:41 -0000

On Fri, 20 Feb 2004, John Baldwin wrote:

> On Thursday 19 February 2004 08:43 pm, Ted Unangst wrote:
> > Hi.  These are some bugs found by Coverity in a static analysis run on the
> > FreeBSD kernel.  All these are use after free bugs.
> 
> Thanks for the excellent bug reports! 

I wonder if the same approach relating to memory allocation and free
checking via static analysis could be applied to locking and unlocking of
locks?  I.e.:

- We don't release locks more than once.

- We don't forget to unlock.

- We hold a lock before accessing certain fields (defined by annotation)
  of a structure.

Robert N M Watson             FreeBSD Core Team, TrustedBSD Projects
robert@fledge.watson.org      Senior Research Scientist, McAfee Research