[IGMP]: workaround for IGMP v1/v2 bug
From: David Stevens <dlstevens@us.ibm.com>
As explained at:
http://www.cs.ucsb.edu/~krishna/igmp_dos/
With IGMP version 1 and 2 it is possible to inject a unicast
report to a client which will make it ignore multicast
reports sent later by the router.
The fix is to only accept the report if is was sent to a
multicast or unicast address.
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index f15e04a..fd939da 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1231,6 +1231,11 @@
if (skb->pkt_type == PACKET_LOOPBACK)
return 0;
+ /* send our report if the MC router may not have heard this report */
+ if (skb->pkt_type != PACKET_MULTICAST &&
+ skb->pkt_type != PACKET_BROADCAST)
+ return 0;
+
if (!pskb_may_pull(skb, sizeof(struct in6_addr)))
return -EINVAL;
