kern/48997: changing link-local address of vlan causes panic

[Takahiro HAYASHI <t.hash425%gmail.com@localhost>]

>Number:         48997
>Category:       kern
>Synopsis:       changing link-local address of vlan causes panic
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jul 15 15:30:00 +0000 2014
>Originator:     Takahiro HAYASHI
>Release:        NetBSD 6.99.47
>Organization:
>Environment:
System: NetBSD  6.99.47 NetBSD 6.99.47 (XHCIDEBUG) #2: Mon Jul 14 02:12:59 JST 
2014  root@halt:/build/head/obj.amd64/sys/arch/amd64/compile/XHCIDEBUG amd64
Architecture: x86_64
Machine: amd64
>Description:
        Changing link-local address of vlan causes panic.

        net/if_vlan.c does not have if_init, so link_control() in
        link_proto.c calls ipf->if_init(=NULL) in case of SIOCALIFADDR.

        I don't think it's worth to change LLADDR of vlan interface because
        parent interface cannot receivce packets that are not for it.
        However, the kernel should not panic anyway.

>How-To-Repeat:
        ifconfig vlan0 create
        ifconfig vlan0 vlan 1 vlanif re0
        ifconfig vlan0 link 0:0:0:0:0:1 active

>Fix:
        A) implement vlan_init(), like as if_tap.c does
        B) avoid exec NULL in link_control()

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