kern/140134: [msdosfs] write and fsck destroy filesystem integrity

[Dominic Fandrey]

The following reply was made to PR kern/140134; it has been noted by GNATS.

From: Dominic Fandrey <kamikaze at bsdforen.de>
To: bug-followup at FreeBSD.org, kamikaze at bsdforen.de
Cc:  
Subject: Re: kern/140134: [msdosfs] write and fsck destroy filesystem integrity
Date: Sun, 08 Nov 2009 12:18:53 +0100

 I just rebuilt world and kernel with RELENG_8 from ~3 hours ago.
 
 Afterwards I repeated the How-To-Repeat procedure and the
 problems shown therein didn't appear.
 
 In the next step I put my Cowon S9 (audio/video player with
 16GB fat32 partition) on the line.
 
 I mounted the device and created a file with touch.
 
 fsck_msdosfs said the drive was fine.
 Windows chkdsk reported the drive was fine.
 
 So the next attempt was to remove the empty file and
 copy a JPG ~2.5MB onto the drive.
 
 fsck_msdosfs reported the following:
 > fsck_msdosfs -n /dev/msdosfs/VALHALLA 
 ** /dev/msdosfs/VALHALLA
 ** Phase 1 - Read and Compare FATs
 ** Phase 2 - Check Cluster Chains
 ** Phase 3 - Checking Directories
 ** Phase 4 - Checking for Lost Files
 Lost cluster chain at cluster 4
 49 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 53
 37 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 90
 9 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 99
 9 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 108
 1126 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1234
 9 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1244
 5 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1248
 49 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1302
 282 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1600
 5 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 1605
 59 Cluster(s) lost
 Reconnect? no
 Clear? no
 Lost cluster chain at cluster 449483
 1 Cluster(s) lost
 Reconnect? no
 Clear? no
 Free space in FSInfo block (-1) not correct (577592)
 Fix? no
 Next free cluster in FSInfo block (2) not free
 Fix? no
 2130 files, 426432 free (577592 clusters)
 
 
 Kinda panicked I ran Windows chkdsk and it reported the drive
 was just fine fine.
 
 fsck_msdosfs still reports the same errors. I conclude that
 writing to msdosfs seems to be fine, now, however fsck_msdosfs
 is a dangerous threat to fat32 file systems.