From: Ben Hutchings <ben@decadent.org.uk>
Date: Mon, 9 Jan 2012 22:06:46 +0000 (-0800)
Subject: igmp: Avoid zero delay when receiving odd mixture of IGMP queries
X-Git-Tag: v3.2.1~5
X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=25c413ad0029ea86008234be28aee33456e53e5b;hp=d2570fc048ca1307e64572c825e0d7908bd60a21

igmp: Avoid zero delay when receiving odd mixture of IGMP queries

commit a8c1f65c79cbbb2f7da782d4c9d15639a9b94b27 upstream.

Commit 5b7c84066733c5dfb0e4016d939757b38de189e4 ('ipv4: correct IGMP
behavior on v3 query during v2-compatibility mode') added yet another
case for query parsing, which can result in max_delay = 0.  Substitute
a value of 1, as in the usual v3 case.

Reported-by: Simon McVittie <smcv@debian.org>
References: http://bugs.debian.org/654876
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index b2ca095cb9da..c3cc64c6f715 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -875,6 +875,8 @@ static void igmp_heard_query(struct in_device *in_dev, struct sk_buff *skb,
 		 * to be intended in a v3 query.
 		 */
 		max_delay = IGMPV3_MRC(ih3->code)*(HZ/IGMP_TIMER_SCALE);
+		if (!max_delay)
+			max_delay = 1;	/* can't mod w/ 0 */
 	} else { /* v3 */
 		if (!pskb_may_pull(skb, sizeof(struct igmpv3_query)))
 			return;