[PATCH 3.2 114/140] net: igmp: fix source address check for IGMPv3 reports

Ben Hutchings
2018-02-28T17:25:11Z

From: Felix Fietkau <nbd@nbd.name>

commit ad23b750933ea7bf962678972a286c78a8fa36aa upstream.

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@chromium.org>
Fixes: a46182b00290 ("net: igmp: Use correct source address on IGMPv3 reports")
Reported-by: Sebastian Gottschall <s.gottschall@dd-wrt.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
net/ipv4/igmp.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -310,7 +310,7 @@ static __be32 igmpv3_get_srcaddr(struct
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);