kern/52526: Panic on "ifconfig athn0 down"

[gson%gson.org@localhost (Andreas Gustafsson)]

>Number:         52526
>Category:       kern
>Synopsis:       Panic on "ifconfig athn0 down"
>Confidential:   no
>Severity:       serious
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Sep 04 17:50:00 +0000 2017
>Originator:     Andreas Gustafsson
>Release:        NetBSD-current, source date 2017.07.21.02.51.12
>Organization:

>Environment:
System: NetBSD
Architecture: i386
Machine: i386
>Description:

I'm trying to get a USB WiFi adapter to work on a NetBSD-current/i386 system,
without much success.  At one point during the process I entered the command
"ifconfig athn0 down", and the machine paniced as follows:

  (gdb) where
  #0  0xc011dd95 in maybe_dump (howto=260) at /bracket/prod/current/src/sys/arch/i386/i386/machdep.c:708
  #1  cpu_reboot (howto=howto@entry=260, bootstr=bootstr@entry=0x0) at /bracket/prod/current/src/sys/arch/i386/i386/machdep.c:729
  #2  0xc092c540 in vpanic (fmt=fmt@entry=0xc0f526ce "trap", ap=ap@entry=0xd9570b08 "\220\vW\331\220\vW\331\001") at /bracket/prod/current/src/sys/kern/subr_prf.c:342
  #3  0xc092c5ca in panic (fmt=fmt@entry=0xc0f526ce "trap") at /bracket/prod/current/src/sys/kern/subr_prf.c:258
  #4  0xc012063f in trap (frame=0xd9570b90) at /bracket/prod/current/src/sys/arch/i386/i386/trap.c:325
  #5  0xc0116f5f in alltraps ()
  #6  0xd9570b90 in ?? ()
  #7  0xc0392a46 in usb_transfer_complete (xfer=xfer@entry=0xc2867624) at /bracket/prod/current/src/sys/dev/usb/usbdi.c:941
  #8  0xc057e516 in uhci_abort_xfer (xfer=<optimized out>, status=<optimized out>) at /bracket/prod/current/src/sys/dev/usb/uhci.c:2423
  #9  0xc0391978 in usbd_ar_pipe (pipe=pipe@entry=0xc27a4e48) at /bracket/prod/current/src/sys/dev/usb/usbdi.c:880
  #10 0xc039275c in usbd_abort_pipe (pipe=0xc27a4e48) at /bracket/prod/current/src/sys/dev/usb/usbdi.c:668
  #11 0xc040d991 in athn_usb_stop_locked (ifp=ifp@entry=0xc2119ae4) at /bracket/prod/current/src/sys/dev/usb/if_athn_usb.c:2937
  #12 0xc040db9b in athn_usb_stop (ifp=0xc2119ae4, disable=0) at /bracket/prod/current/src/sys/dev/usb/if_athn_usb.c:2907
  #13 0xc040e6f7 in athn_usb_ioctl (ifp=0xc2119ae4, cmd=2156947728, data=0xc29af3c8) at /bracket/prod/current/src/sys/dev/usb/if_athn_usb.c:2676
  #14 0xc09c217e in doifioctl (so=0xc29a26a4, cmd=2156947728, data=0xc29af3c8, l=0xc27cc2a0) at /bracket/prod/current/src/sys/net/if.c:3042
  #15 0xc094381c in soo_ioctl (fp=0xc2988bc0, cmd=2156947728, data=0xc29af3c8) at /bracket/prod/current/src/sys/kern/sys_socket.c:202
  #16 0xc0937714 in sys_ioctl (l=0xc27cc2a0, uap=0xd9570f68, retval=0xd9570f60) at /bracket/prod/current/src/sys/kern/sys_generic.c:671
  #17 0xc015a37d in sy_call (rval=0xd9570f60, uap=0xd9570f68, l=0xc27cc2a0, sy=0xc12390d8 <sysent+1080>) at /bracket/prod/current/src/sys/sys/syscallvar.h:65
  #18 sy_invoke (code=54, rval=0xd9570f60, uap=0xd9570f68, l=0xc27cc2a0, sy=0xc12390d8 <sysent+1080>) at /bracket/prod/current/src/sys/sys/syscallvar.h:94
  #19 syscall (frame=0xd9570fa8) at /bracket/prod/current/src/sys/arch/x86/x86/syscall.c:144
  #20 0xc0100696 in Xsyscall ()
  #21 0xd9570fa8 in ?? ()

This is the same Comfast CF-WU871N adapter as in PR 51531.

>How-To-Repeat:

>Fix: