kern/119638: [ffs] fsck_ffs -b 32 doesn't repair primary superblock

[Yoshihiro Ota]

The following reply was made to PR kern/119638; it has been noted by GNATS.

From: Yoshihiro Ota <ota at j.email.ne.jp>
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: kern/119638: [ffs] fsck_ffs -b 32 doesn't repair primary
 superblock
Date: Sat, 19 Apr 2008 04:59:53 -0400

 When you provide a super block with -b option, fsck_ffs does far less sanity check compare to normal mode.  Indeed, it checks only the UFS magic numbers.  Then, it assumes that the supplied super block is correct and try to adjust based on the block given.
 
 You provided a wrong block which coincidentally fulfilled this simple sanity check.  fsck_ffs corrected based on the information given.  However, as you provided wrong data, it could only result corrupting the file system information.
 
 This is not a bug but an operational mistake.
 
 Hiro