panic: igmp_v3_dispatch_general_query: called when version 2

[deeptech71 at gmail.com]

Bruce Simpson wrote:
> I may not get free time to fix this right away, are you able to test a
> patch when I can make one available?

Sure.

> It would be helpful if you could confirm, with a tcpdump capture forked
> from single user mode, if your FreeBSD host is receiving an IGMPv2 query
> when this problem is triggered.

How do I do that?
But it's not "when" it is triggered, but rather "if... ever".

> It sounds like your university LAN may well have an IGMPv2 capable
> multicast router present on the network. If you could double confirm
> this, via packet capture, that would be great.

Does this dump(snip) tell?

18:21:19.837291 IP binhlinh.teteny.bme.hu.50530 > 224.0.0.253.3544: UDP, 
length 40
18:21:23.450396 IP imperator.teteny.bme.hu.51605 > 224.0.0.252.5355: 
UDP, length 23
18:21:42.411459 IP lxandr.teteny.bme.hu.51045 > 224.0.0.252.5355: UDP, 
length 25
18:21:42.512624 IP lxandr.teteny.bme.hu.51045 > 224.0.0.252.5355: UDP, 
length 25
18:21:45.171807 IP lxandr.teteny.bme.hu.55288 > 224.0.0.252.5355: UDP, 
length 25
18:21:59.632491 IP 192.168.77.2 > ALL-SYSTEMS.MCAST.NET: igmp query v2
18:22:01.336805 IP tudylaptop.teteny.elte.hu > 224.0.0.251: igmp v2 
report 224.0.0.251
18:22:06.356016 IP 192.168.77.2 > ALL-SYSTEMS.MCAST.NET: igmp query v2
18:22:06.364706 IP 192.168.77.2 > ALL-SYSTEMS.MCAST.NET: igmp query v2
18:22:08.851672 IP scylla.teteny.bme.hu.mdns > 224.0.0.251.mdns: 0 PTR 
(QM)? 21.64.168.192.in-addr.arpa. (44)
18:22:08.873333 IP marhapalinka.teteny.elte.hu > 224.0.0.252: igmp v2 
report 224.0.0.252
18:22:10.010465 IP fecsketurmix.teteny.elte.hu > 224.0.0.251: igmp v2 
report 224.0.0.251
18:22:10.649814 IP ani.teteny.elte.hu.55741 > 224.0.0.252.5355: UDP, 
length 21
18:22:10.750069 IP ani.teteny.elte.hu.55741 > 224.0.0.252.5355: UDP, 
length 21
18:25:07.368543 IP 192.168.77.2 > 224.0.0.252: igmp query v2 [max resp 
time 10] [gaddr 224.0.0.252]

> [I]f there is anything unusual about the format of the IGMPv2 queries from
> your university's vendor equipment, that would be good to know too.

Heh. How does that relate to the kernel code assigning a v3 handler to a 
v2 packet? (Looks something like that to me.) What if I say yes, and 
what if I say no? :)

Anyways, I'll try to contact the admin about that.