kern/42982: crash on detaching network interfaces like wm(4)

[yamt%NetBSD.org@localhost]

>Number:         42982
>Category:       kern
>Synopsis:       crash on detaching network interfaces like wm(4)
>Confidential:   no
>Severity:       critical
>Priority:       high
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 16 03:00:00 +0000 2010
>Originator:     YAMAMOTO Takashi
>Release:        NetBSD-current
>Organization:
        
>Environment:
        
        
>Description:
        on detach, some drivers including wm(4) calls ether_ifdetach
        and then if_detach.
        ether_ifdetach destroys if_mowner.
        if_detach might send out packets (eg. for ipv6)
        via ether_output, which uses if_mowner, which is already stale
        at this point.
>How-To-Repeat:
        shutdown a system with MBUFTRACE and ipv6?
>Fix:
        

>Unformatted: