af_packet: do not accept mc address smaller then dev->addr_len in packet_mc_add()

There is no point of accepting an address of smaller length than dev->addr_len
here. Therefore change this for stonger check.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 2f03693..e2d1def 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1734,7 +1734,7 @@
 		goto done;
 
 	err = -EINVAL;
-	if (mreq->mr_alen > dev->addr_len)
+	if (mreq->mr_alen != dev->addr_len)
 		goto done;
 
 	err = -ENOBUFS;