misc/89534: ifconfig causes page fault

[Stuart Weaver]

>Number:         89534
>Category:       misc
>Synopsis:       ifconfig causes page fault
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Fri Nov 25 15:40:08 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Stuart Weaver
>Release:        FreeBSD 6.0-RELEASE i386
>Organization:
N/A
>Environment:
FreeBSD zyon.sweaver.net 6.0-RELEASE FreeBSD 6.0-RELEASE #0: Thu Nov 3 09:36:13 UTC 2005 root at x64.samsco.home:/usr/obj/usr/src/sys/GENERIC i386
>Description:
              The machine the problem occures on is running a wireless access point with a brigde between the wi0 and vr0 devices.  Wen I disable the AP and then run ifconfig imdeiately afterwards the machine crashes.

I manualy copied the following from the console, there may be errors:

Fatal trap 12: page fault wile in kernel mode
fault virtual address   = 0xc1d6e024
fault code              = supervisor read, pate not present
instruction pointer     = 0x20:0xc06bc581
stack pointer           = 0x28:0xdd6cd6d4
frame pointer           = 0x28:0xdd6cd724
code segmet             = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 857 (ifconfig)
trap number             = 12
panic: page fault
Uptime: 13m8s
Dumping 459 MB (2 chunks)
  chunk 0: 1MB (159 pages) ... ok
  chunk 1: 479MB (122608 pages) 463 447 431 415 399 383 367 335 319 303 287 271
255 239 207 191 175 159 143 127 111 95 79 63 47 31 15 ... ok
 
Dump complete

>How-To-Repeat:
                I use the following steps to repeat the problem.
Bring up wi0 in hostAP mode:

kldload bridge
kldload wlan_wep
sysctl net.link.ether.bridge.enable=1
sysctl net.link.ether.bridge_cfg="wi0 vr0"
sysctl net.inet.ip.forwarding=1
ifconfig wi0 inet SOMEIPADDR netmask 255.255.255.255 ssid SOMESID \
   media DS/11Mbps mode 11b mediaopt hostap stationname SOMENAME \
   channel 11 wepmode on wepkey 1:0xSOMEKEY \
   wepkey 2:0xANOTHERKEY wepkey 3:0xANDANOTHER \
   wepkey 4:0xANDONEMORE weptxkey 1 up


Now bring wi0 down, unload modules and disable forwarding:
  ifconfig wi0 down
  kldunload bridge
  kldunload wlan_wep
  sysctl net.inet.ip.forwarding=0

Running ifconfig immediately after-wards seems to cause the problem:
  ifconfig
>Fix:
              
>Release-Note:
>Audit-Trail:
>Unformatted: