Date: Wed, 09 Sep 2009 21:11:29 -0000 From: Stef Walter <stef-list@memberwebs.com> To: "freebsd-net@FreeBSD.org" <freebsd-net@freebsd.org> Subject: [patch] Multicast: uninited memory used in filter at IP_DROP_MEMBERSHIP + IP_ADD_MEMBERSHIP Resent-Message-ID: <none>
| raw e-mail | index | archive | help
[-- Attachment #1 --]
If a multicast caller does an IP_DROP_MEMBERSHIP followed by a
IP_ADD_MEMBERSHIP, often an uninitialized filter is used for the
in_mfilter passed to in_joingroup_locked() in netinet/in_mcast.c.
The IP_ADD_MEMBERSHIP and IP_DROP_MEMBERSHIP have simple in_mreq input,
and are not using SSM or any of the new IGMPv3 features.
This results in the following behavior shown by ifmcstat. Before the
drop + add you can see the following groups for the northstar1
interface. Note that 224.0.0.5 (ie: OSPF-ALL.MCAST.NET) is subscribed
with an empty exclude filter as you would expect from simple ASM mode:
> # ifmcstat -i northstar1
> northstar1:
> inet 172.28.1.66
> igmpv3 flags=0<> rv 2 qi 125 qri 10 uri 3
> group 224.0.0.5 mode exclude
> group 224.0.0.1 mode exclude
After the drop + add, it looks like the following. Note that now
224.0.0.5 is subscribed with an empty *include* filter which results in
no packets received.
> # ifmcstat -i northstar1
> northstar1:
> inet 172.28.1.66
> igmpv3 flags=0<> rv 2 qi 125 qri 10 uri 3
> group 224.0.0.1 mode exclude
> group 224.0.0.5 mode include
uname: FreeBSD portillo-gate.ws.local 8.0-BETA3 FreeBSD 8.0-BETA3 #24:
Wed Sep 9 15:01:39 UTC 2009
root@portillo-gate.ws.local:/usr/src/sys/i386/compile/PORTILLO i386
Patch is attached which fixes the problem. Is this the right approach?
If not, I hope it helps highlight the problem area.
Cheers,
Stef
[-- Attachment #2 --]
--- sys/netinet/in_mcast.c.orig 2009-08-03 08:13:06.000000000 +0000
+++ sys/netinet/in_mcast.c 2009-09-09 15:01:24.000000000 +0000
@@ -2024,6 +2050,9 @@
error = ENOMEM;
goto out_imo_free;
}
+ } else if (is_new) {
+ /* Old style ASM filter mode is always exclude */
+ imf_init(imf, MCAST_UNDEFINED, MCAST_EXCLUDE);
}
/*