From owner-freebsd-hackers Tue Nov 26 04:11:37 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id EAA29651 for hackers-outgoing; Tue, 26 Nov 1996 04:11:37 -0800 (PST) Received: from godzilla.zeta.org.au (godzilla.zeta.org.au [203.2.228.19]) by freefall.freebsd.org (8.7.5/8.7.3) with ESMTP id EAA29552 for ; Tue, 26 Nov 1996 04:10:16 -0800 (PST) Received: (from bde@localhost) by godzilla.zeta.org.au (8.8.3/8.6.9) id XAA06641; Tue, 26 Nov 1996 23:05:10 +1100 Date: Tue, 26 Nov 1996 23:05:10 +1100 From: Bruce Evans Message-Id: <199611261205.XAA06641@godzilla.zeta.org.au> To: jkh@time.cdrom.com, rnordier@iafrica.com Subject: Re: A simple way to crash your system. Cc: grog@lemis.de, hackers@FreeBSD.ORG Sender: owner-hackers@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk >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. That can't be the problem, since FreeBSD ignores the geometry in both the driver and in msdosfs. >Unless someone is aware of the problem being more general, it may MAXBSIZE = 16384. I'm not sure exactly what using larger blocks breaks, if anything (blocks up to MAXPHYS=64K are sometimes used and work OK), but ufs is careful to reject file systems with a larger block size. Bruce