From owner-freebsd-bugs@FreeBSD.ORG  Wed Sep 10 15:30:02 2008
Return-Path: <owner-freebsd-bugs@FreeBSD.ORG>
Delivered-To: freebsd-bugs@hub.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 1475E1065678
	for <freebsd-bugs@hub.freebsd.org>;
	Wed, 10 Sep 2008 15:30:02 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org
	[IPv6:2001:4f8:fff6::28])
	by mx1.freebsd.org (Postfix) with ESMTP id E31248FC21
	for <freebsd-bugs@hub.freebsd.org>;
	Wed, 10 Sep 2008 15:30:01 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1])
	by freefall.freebsd.org (8.14.2/8.14.2) with ESMTP id m8AFU1kD041788
	for <freebsd-bugs@freefall.freebsd.org>; Wed, 10 Sep 2008 15:30:01 GMT
	(envelope-from gnats@freefall.freebsd.org)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.14.2/8.14.1/Submit) id m8AFU163041787;
	Wed, 10 Sep 2008 15:30:01 GMT (envelope-from gnats)
Resent-Date: Wed, 10 Sep 2008 15:30:01 GMT
Resent-Message-Id: <200809101530.m8AFU163041787@freefall.freebsd.org>
Resent-From: FreeBSD-gnats-submit@FreeBSD.org (GNATS Filer)
Resent-To: freebsd-bugs@FreeBSD.org
Resent-Reply-To: FreeBSD-gnats-submit@FreeBSD.org,
	Anatoly Borodin <anatoly.borodin@gmail.com>
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 6456D1065671
	for <freebsd-gnats-submit@FreeBSD.org>;
	Wed, 10 Sep 2008 15:26:44 +0000 (UTC)
	(envelope-from nobody@FreeBSD.org)
Received: from www.freebsd.org (www.freebsd.org [IPv6:2001:4f8:fff6::21])
	by mx1.freebsd.org (Postfix) with ESMTP id 5151A8FC1E
	for <freebsd-gnats-submit@FreeBSD.org>;
	Wed, 10 Sep 2008 15:26:44 +0000 (UTC)
	(envelope-from nobody@FreeBSD.org)
Received: from www.freebsd.org (localhost [127.0.0.1])
	by www.freebsd.org (8.14.2/8.14.2) with ESMTP id m8AFQiBV082062
	for <freebsd-gnats-submit@FreeBSD.org>; Wed, 10 Sep 2008 15:26:44 GMT
	(envelope-from nobody@www.freebsd.org)
Received: (from nobody@localhost)
	by www.freebsd.org (8.14.2/8.14.1/Submit) id m8AFQhC6082061;
	Wed, 10 Sep 2008 15:26:43 GMT (envelope-from nobody)
Message-Id: <200809101526.m8AFQhC6082061@www.freebsd.org>
Date: Wed, 10 Sep 2008 15:26:43 GMT
From: Anatoly Borodin <anatoly.borodin@gmail.com>
To: freebsd-gnats-submit@FreeBSD.org
X-Send-Pr-Version: www-3.1
Cc: 
Subject: misc/127270: fsck_msdosfs may crash
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: Wed, 10 Sep 2008 15:30:02 -0000


>Number:         127270
>Category:       misc
>Synopsis:       fsck_msdosfs may crash
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Sep 10 15:30:01 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Anatoly Borodin
>Release:        7.1-PRERELEASE
>Organization:
>Environment:
FreeBSD hp.home 7.1-PRERELEASE FreeBSD 7.1-PRERELEASE #0: Mon Sep  1 16:07:24 EEST 2008     anatoly.borodin@gmail.com:/usr/obj/usr/src/sys/GENERIC  i386

>Description:
I use some FAT32 filesystem from a file image. It has errors, so I tried to check it with fsck_msdosfs /dev/md0 and got this:

** /dev/md0
Floating exception (core dumped)

I compiled fsck_msdosfs with debug information and found the faulty code block at /usr/src/sbin/fsck_msdosfs/boot.c:174

        boot->ClusterOffset = (boot->RootDirEnts * 32 + boot->BytesPerSec - 1)
            / boot->BytesPerSec
            + boot->ResSectors
            + boot->FATs * boot->FATsecs
            - CLUST_FIRST * boot->SecPerClust;

It fails because in my case boot->BytesPerSec == 0. IMHO such condition should be checked, fixed in the FS, but not crashed.

>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:
>Unformatted: