netdev - [PATCH] net: igmp: fix source address check for IGMPv3 reports

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Date:   Fri, 19 Jan 2018 11:50:46 +0100
From:   Felix Fietkau <nbd@....name>
To:     netdev@...r.kernel.org
Cc:     cernekee@...omium.org, s.gottschall@...wrt.com
Subject: [PATCH] net: igmp: fix source address check for IGMPv3 reports

Commit "net: igmp: Use correct source address on IGMPv3 reports"
introduced a check to validate the source address of locally generated
IGMPv3 packets.
Instead of checking the local interface address directly, it uses
inet_ifa_match(fl4->saddr, ifa), which checks if the address is on the
local subnet (or equal to the point-to-point address if used).

This breaks for point-to-point interfaces, so check against
ifa->ifa_local directly.

Cc: Kevin Cernekee <cernekee@...omium.org>
Fixes: a46182b00290 ("net: igmp: Use correct source address on IGMPv3 reports")
Reported-by: Sebastian Gottschall <s.gottschall@...wrt.com>
Signed-off-by: Felix Fietkau <nbd@....name>
---
 net/ipv4/igmp.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 726f6b608274..2d49717a7421 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -332,7 +332,7 @@ static __be32 igmpv3_get_srcaddr(struct net_device *dev,
 		return htonl(INADDR_ANY);

 	for_ifa(in_dev) {
-		if (inet_ifa_match(fl4->saddr, ifa))
+		if (fl4->saddr == ifa->ifa_local)
 			return fl4->saddr;
 	} endfor_ifa(in_dev);

-- 
2.14.2