kern/120044: incorrect MSDOSFS label fries administrative access to GEOM

[Bernard Steiner]

>Number:         120044
>Category:       kern
>Synopsis:       incorrect MSDOSFS label fries administrative access to GEOM
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sun Jan 27 15:40:11 UTC 2008
>Closed-Date:
>Last-Modified:
>Originator:     Bernard Steiner
>Release:        6.3-STABLE
>Organization:
>Environment:
FreeBSD grimma.anydomain.de 6.3-STABLE FreeBSD 6.3-STABLE #13: Fri Jan 25 20:23:36 CET 2008     root at grimma.anydomain.de:/usr/obj/usr/src/sys/GRIMMA  amd64

>Description:
An unexpected msdosfs label can fry GEOM.
I have an old memory stick which happens to have (had ;-) a non-standard MSDOSFS label on it, viz:

Jan 26 11:28:34 grimma kernel: umass0: vendor 0x0c76 product 0x0005, rev 1.10/1.00, addr 3
Jan 26 11:28:34 grimma kernel: da0 at umass-sim0 bus 0 target 0 lun 0
Jan 26 11:28:34 grimma kernel: da0: (JetFlash Transcend 1.00) Removable Direct Access SCSI-2 device 
Jan 26 11:28:34 grimma kernel: da0: 1.000MB/s transfers
Jan 26 11:28:34 grimma kernel: da0: 61MB (126600 512 byte sectors: 64H 32S/T 61C)
Jan 26 11:28:35 grimma kernel: GEOM_LABEL: Label for provider da0 is msdosfs/(A0)(EA)(FF)(FF)(FF).

(I replaced less-than and greater-than in those lines)

Doing something like "gmirror status" while that memory stick is inserted yields a nice
"Cannot get GEOM tree: Unknown error: -1." Note that the operation of the actual gmirror (and glabel, geli) devices is not affected afaik.

The same stick works perfectly after being re-mlabel-d to a decent name.
Stops working if the label is re-set to those unprintables...

>How-To-Repeat:
mlabel an msdosfs filesystem to 0xa0 0xea 0xff 0xff 0xff
>Fix:


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