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

commit a8c1f65 upstream.

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 <>
Signed-off-by: Ben Hutchings <>
Signed-off-by: David S. Miller <>
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commit dd9f9823b61ce894163433380ffcfc28eaf6e9c5 1 parent 8dccddb
Ben Hutchings authored gregkh committed
Showing with 2 additions and 0 deletions.
  1. +2 −0  net/ipv4/igmp.c
2  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)))
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