From owner-freebsd-bugs@FreeBSD.ORG  Fri Aug 28 22:19:38 2009
Return-Path: <owner-freebsd-bugs@FreeBSD.ORG>
Delivered-To: freebsd-bugs@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 072691065672
	for <freebsd-bugs@FreeBSD.org>; Fri, 28 Aug 2009 22:19:38 +0000 (UTC)
	(envelope-from bruce@cran.org.uk)
Received: from muon.cran.org.uk (muon.cran.org.uk [66.246.138.153])
	by mx1.freebsd.org (Postfix) with ESMTP id D3B1A8FC27
	for <freebsd-bugs@FreeBSD.org>; Fri, 28 Aug 2009 22:19:37 +0000 (UTC)
Received: from gluon.draftnet (87-194-158-129.bethere.co.uk [87.194.158.129])
	(using TLSv1 with cipher DHE-RSA-AES128-SHA (128/128 bits))
	(No client certificate requested)
	by muon.cran.org.uk (Postfix) with ESMTPSA id 223E4851A;
	Fri, 28 Aug 2009 22:01:22 +0000 (UTC)
Date: Fri, 28 Aug 2009 23:01:08 +0100
From: Bruce Cran <bruce@cran.org.uk>
To: Chris St Denis <chris@smartt.com>
Message-ID: <20090828230108.2ac0145b@gluon.draftnet>
In-Reply-To: <200908281810.n7SIA6Oq066948@freefall.freebsd.org>
References: <200908281810.n7SIA6Oq066948@freefall.freebsd.org>
X-Mailer: Claws Mail 3.7.2 (GTK+ 2.16.4; i386-portbld-freebsd7.2)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: freebsd-bugs@FreeBSD.org
Subject: Re: bin/130343: top(1): kvm_open: cannot open /proc/42997/mem
 corrupts screen output
X-BeenThere: freebsd-bugs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Bug reports <freebsd-bugs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-bugs>
List-Post: <mailto:freebsd-bugs@freebsd.org>
List-Help: <mailto:freebsd-bugs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 28 Aug 2009 22:19:38 -0000

It looks the "-a" option is triggering the fault.  kvm_getargv
(in lib/libkvm/kvm_proc.c) attempts to read the argv array
using sysctl; if that fails then it calls kvm_doargv which attempts to
read the array from the process' memory (via kvm_uread) by
opening /proc/%d/mem (kvm_proc.c line 997).

-- 
Bruce Cran