kern/89966: mounting ntfs causes kernel panic in some cases

[H. Matsuo]

>Number:         89966
>Category:       kern
>Synopsis:       mounting ntfs causes kernel panic in some cases
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Dec 05 09:50:01 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     H. Matsuo
>Release:        6.0-STABLE
>Organization:
>Environment:
FreeBSD racco.zoo 6.0-STABLE FreeBSD 6.0-STABLE #1: Sun Dec  4 18:51:43 JST 2005     root at racco.zoo:/mnt/misc/freebsd-6/obj/mnt/misc/freebsd-6/src/sys/GENERIC\
 i386 i386 Mobile Intel(R) Pentium(R) 4 - M CPU 2.00GHz FreeBSD
>Description:
When tring to re-mount *mounted* filesystem again, kernel does not return
ERROR, or panic in some cases (with option -o ro).

Please see below.  In case 1-3 kernel reacts properly, but in case 4-5
response of kernel seems to be odd.  In case 6, kernel panic happens.

-----------------------------------
[CASE1]
# mount -t ufs /dev/da0s4d /mnt/misc
# mount -t ufs /dev/da0s4d /mnt/misc
mount: /dev/da0s4d: Operation not permitted
    (kernel returns ERROR: this is an expected response, no problem.)

[CASE2]
# mount -t msdosfs /dev/da0s3 /mnt/win3
# mount -t msdosfs /dev/da0s3 /mnt/win3
mount_msdosfs: /dev/da0s3: Operation not permitted
    (kernel returns ERROR: this is an expected response, no problem.)

[CASE3]
# mount -t ntfs /dev/ad0s1 /mnt/win1
# mount -t ntfs /dev/ad0s1 /mnt/win1
mount_ntfs: /dev/ad0s1: Operation not permitted
    (kernel returns ERROR: this is an expected response, no problem.)

[CASE4]
# mount -t ufs -o ro /dev/da0s4d /mnt/misc
# mount -t ufs -o ro /dev/da0s4d /mnt/misc
    (kernel does not return ERROR, why?)
# df
Filesystem  1K-blocks      Used    Avail Capacity  Mounted on
/dev/ad0s3a    118766     79268    29998    73%    /
devfs               1         1        0   100%    /dev
/dev/ad0s3d   2675918   1498266   963580    61%    /usr
/dev/ad0s3e    168366     36918   117980    24%    /var
/dev/ad0s3f    287888    141996   122862    54%    /home
procfs              4         4        0   100%    /proc
/dev/da0s4d   9915754   4663748  4458746    51%    /mnt/misc
/dev/da0s4d   9915754   4663748  4458746    51%    /mnt/misc
    (/mnt/misc line appears twice. Is this no problem?)

[CASE5]
# mount -t msdosfs -o ro /dev/da0s3 /mnt/win3
# mount -t msdosfs -o ro /dev/da0s3 /mnt/win3
# df
Filesystem  1K-blocks      Used    Avail Capacity  Mounted on
/dev/ad0s3a    118766     79268    29998    73%    /
devfs               1         1        0   100%    /dev
/dev/ad0s3d   2675918   1498266   963580    61%    /usr
/dev/ad0s3e    168366     36916   117982    24%    /var
/dev/ad0s3f    287888    141996   122862    54%    /home
procfs              4         4        0   100%    /proc
/dev/da0s3    5114732   1087768  4026964    21%    /mnt/win3
/dev/da0s3    5114732   1087768  4026964    21%    /mnt/win3
    (same as CASE4)

[CASE6]
# mount -t ntfs -o ro /dev/ad0s1 /mnt/win1
# mount -t ntfs -o ro /dev/ad0s1 /mnt/win1
<<kernel panic!!>>

>How-To-Repeat:
# mount -t ntfs -o ro /dev/ad0s1 /mnt/win1
# mount -t ntfs -o ro /dev/ad0s1 /mnt/win1
<<kernel panic!!>>
>Fix:
I don't know.
>Release-Note:
>Audit-Trail:
>Unformatted: