From: David Stevens <dlstevens@us.ibm.com>
Date: Sat, 3 Dec 2005 04:32:59 +0000 (-0800)
Subject: [IGMP]: workaround for IGMP v1/v2 bug
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=24c6927505ca77ee4ac25fb31dcd56f6506979ed;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git

[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/ipv4/igmp.c b/net/ipv4/igmp.c
index c04607b49212..4a195c724f01 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -897,7 +897,10 @@ int igmp_rcv(struct sk_buff *skb)
 		/* Is it our report looped back? */
 		if (((struct rtable*)skb->dst)->fl.iif == 0)
 			break;
-		igmp_heard_report(in_dev, ih->group);
+		/* don't rely on MC router hearing unicast reports */
+		if (skb->pkt_type == PACKET_MULTICAST ||
+		    skb->pkt_type == PACKET_BROADCAST)
+			igmp_heard_report(in_dev, ih->group);
 		break;
 	case IGMP_PIM:
 #ifdef CONFIG_IP_PIMSM_V1
diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index f15e04ad026e..fd939da090c4 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1231,6 +1231,11 @@ int igmp6_event_report(struct sk_buff *skb)
 	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;