[PATCH 3.16.y-ckt 061/118] bridge: mdb: zero out the local br_ip variable before use

[Luis Henriques]

3.16.7-ckt16 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <razor at blackwall.org>

commit f1158b74e54f2e2462ba5e2f45a118246d9d5b43 upstream.

Since commit b0e9a30dd669 ("bridge: Add vlan id to multicast groups")
there's a check in br_ip_equal() for a matching vlan id, but the mdb
functions were not modified to use (or at least zero it) so when an
entry was added it would have a garbage vlan id (from the local br_ip
variable in __br_mdb_add/del) and this would prevent it from being
matched and also deleted. So zero out the whole local ip var to protect
ourselves from future changes and also to fix the current bug, since
there's no vlan id support in the mdb uapi - use always vlan id 0.
Example before patch:
root at debian:~# bridge mdb add dev br0 port eth1 grp 239.0.0.1 permanent
root at debian:~# bridge mdb
dev br0 port eth1 grp 239.0.0.1 permanent
root at debian:~# bridge mdb del dev br0 port eth1 grp 239.0.0.1 permanent
RTNETLINK answers: Invalid argument

After patch:
root at debian:~# bridge mdb add dev br0 port eth1 grp 239.0.0.1 permanent
root at debian:~# bridge mdb
dev br0 port eth1 grp 239.0.0.1 permanent
root at debian:~# bridge mdb del dev br0 port eth1 grp 239.0.0.1 permanent
root at debian:~# bridge mdb

Signed-off-by: Nikolay Aleksandrov <razor at blackwall.org>
Fixes: b0e9a30dd669 ("bridge: Add vlan id to multicast groups")
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 net/bridge/br_mdb.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/bridge/br_mdb.c b/net/bridge/br_mdb.c
index 21927405cf4e..4754f2d32bb3 100644
--- a/net/bridge/br_mdb.c
+++ b/net/bridge/br_mdb.c
@@ -373,6 +373,7 @@ static int __br_mdb_add(struct net *net, struct net_bridge *br,
 	if (!p || p->br != br || p->state == BR_STATE_DISABLED)
 		return -EINVAL;
 
+	memset(&ip, 0, sizeof(ip));
 	ip.proto = entry->addr.proto;
 	if (ip.proto == htons(ETH_P_IP))
 		ip.u.ip4 = entry->addr.u.ip4;
@@ -419,6 +420,7 @@ static int __br_mdb_del(struct net_bridge *br, struct br_mdb_entry *entry)
 	if (!netif_running(br->dev) || br->multicast_disabled)
 		return -EINVAL;
 
+	memset(&ip, 0, sizeof(ip));
 	ip.proto = entry->addr.proto;
 	if (ip.proto == htons(ETH_P_IP)) {
 		if (timer_pending(&br->ip4_other_query.timer))