From owner-freebsd-hackers Tue Nov 26 02:52:28 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id CAA20079 for hackers-outgoing; Tue, 26 Nov 1996 02:52:28 -0800 (PST) Received: from eac.iafrica.com (196-7-192-147.iafrica.com [196.7.192.147]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id CAA20067 for ; Tue, 26 Nov 1996 02:52:15 -0800 (PST) Received: (from rnordier@localhost) by eac.iafrica.com (8.7.6/8.6.12) id MAA02308; Tue, 26 Nov 1996 12:49:03 +0200 (SAT) From: Robert Nordier Message-Id: <199611261049.MAA02308@eac.iafrica.com> Subject: Re: A simple way to crash your system. In-Reply-To: <11813.848999125@time.cdrom.com> from "Jordan K. Hubbard" at "Nov 26, 96 01:05:25 am" To: jkh@time.cdrom.com (Jordan K. Hubbard) Date: Tue, 26 Nov 1996 12:49:02 +0200 (SAT) Cc: grog@lemis.de, hackers@freebsd.org X-Mailer: ELM [version 2.4ME+ PL28 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk Jordan K. Hubbard wrote: > > - remove it and announce the fact on -announce. > > That won't last more than a week - people don't search the archives > and memories are short. > > > - make it read-only (will this help?) > > It already is read-only by default if you mount it from the label > editor. People change it back the minute they want to write on > it. :-) > > I'm not sure what to do. Putting it into the release notes under a > "STILL BROKEN" section seems also excessive.. :) FWIW, the table below represents a couple of months of collecting data from users on -questions, who reported that the msdosfs had seriously corrupted a UFS partition. DRIVE DOS START DOS END cyl head sect || cyl head sect cyl head sect size ------------------------------------------------------------------- wd0 | 525 | 64 | 63 || 0 | 1 | 1 | 126 | 63 | 63 | 512001 wd0 | 2099 | 64 | 63 || 0 | 1 | 1 | 189 | 63 | 63 | 766017 same drive || 250 | 0 | 1 | 523 | 63 | 63 | 1104768 wd0 | 788 | 64 | 63 || 0 | 1 | 1 | 787 | 63 | 63 | 3177153 wd0 | 621 | 64 | 63 || 0 | 1 | 1 | 619 | 63 | 63 | 2499777 wd0 | 525 | 64 | 63 || 0 | 1 | 1 | 523 | 63 | 63 | 2112705 *All* problems occurred with the DOS FS on a 64/63 IDE drive. FIPS was not necessarily used. In one case, the corrupted UFS fs was actually on another drive. Unless someone is aware of the problem being more general, it may be worth patching the msdosfs code to (by default) refuse to access DOS FSes with > 16 sectors per cluster on such drives. Or at least warn that 64/63 IDE setups are particularly vulnerable. -- Robert Nordier