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

Commit 5b7c840 ('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 <[email protected]> References: http://bugs.debian.org/654876 Signed-off-by: Ben Hutchings <[email protected]> Signed-off-by: David S. Miller <[email protected]>
kawasaki · Jan 9, 2012 · a8c1f65 · a8c1f65
1 parent e5686ad
commit a8c1f65
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
@@ -880,6 +880,8 @@ 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;