kern/138666: [multicast] [panic] not working multicast through igmpproxy

[Andriy Syrovenko]

Hi,

Well, turning off the transmit checksum offloading on the upstream
interface solves the problem with IP checksums of IGMP report and
leave messages always being 0. So after issuing the

ifconfig re1 -txcsum

command, the proxy successfully subscribes to receiving multicast
streams, and I can see multicast UDP traffic coming in on the upstream
interface. However there is another serious problem. Shortly alfter my
router starts forwarding multicast traffic kernel crashes. The crash
may happen either immediately when I press the play button in my IPTV
player, or just after several channel switches. You can find crash
reports in the attached files. They are almost identical, differing
only in whether the pf module is loaded.


The interesting part of the story is if I block incoming UDP multicast
traffic using something like

block in quick inet proto udp from any to 224.0.0.0/4

in my pf.conf, system remains stable. But as soon as I comment the
rule and reload pf, kernel crashes. I suspect the problem is not
strictly related to the igmp processing, but to the multicast routing
in general. Probably something wrong with thread synchronization. My
system is a dual-core Intel Atom.

Another interesting observation is when my BSD box is disconnected
from the upstream router, I can see only IGMPv3 messages going out the
upstream interface, even despite the fact that igmpproxy supports
IGMPv2 only.

br,
Andrey
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