misc/154943: ifconfig gifX create on existing gifX clears IP

[Piotr KUCHARSKI]

>Number:         154943
>Category:       misc
>Synopsis:       ifconfig gifX create on existing gifX clears IP
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Mon Feb 21 17:30:09 UTC 2011
>Closed-Date:
>Last-Modified:
>Originator:     Piotr KUCHARSKI
>Release:        FreeBSD 8.2-PRERELEASE amd64
>Organization:
>Environment:
System: FreeBSD 8.2-PRERELEASE #18 r218734M: Wed Feb 16 18:19:49 CET 2011
with zfs 28 patches applied (though it should not matter)

>Description:
	erroneous 'ifconfig gifX create' (on a wrong gif interface) clears
  existing IP assignments (which of course destroys all tcp connections using it)

  this seems like a regression from 8.1

>How-To-Repeat:
# ifconfig gif5 create
# ifconfig gif5 tunnel 172.16.0.1 172.31.255.254
# ifconfig gif5 10.0.0.1 10.0.0.2
# ifconfig gif5
gif5: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1280
        tunnel inet 172.16.0.1 --> 172.31.255.254
        inet 10.0.0.1 --> 10.0.0.2 netmask 0xff000000 
        options=1<ACCEPT_REV_ETHIP_VER>
# ping 10.0.0.2  # just to verify it works, even if it should not matter
64 bytes from 10.0.0.2: icmp_seq=0 ttl=64 time=27.267 ms
# ifconfig gif5 create
ifconfig: ioctl (SIOCAIFADDR): Destination address required
# ifconfig gif5
gif5: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1280
        tunnel inet 172.16.0.1 --> 172.31.255.254
        options=1<ACCEPT_REV_ETHIP_VER>
>Fix:

	


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