net: IP_MULTICAST_IF setsockopt now recognizes struct mreq

Until now, struct mreq has not been recognized and it was worked with
as with struct in_addr. That means imr_multiaddr was copied to
imr_address. So do recognize struct mreq here and copy that correctly.
Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ip_sockglue.c

@@ -673,11 +673,16 @@ static int do_ip_setsockopt(struct sock *sk, int level,
 				break;
 		} else {
 			memset(&mreq, 0, sizeof(mreq));
-			if (optlen >= sizeof(struct in_addr) &&
-			    copy_from_user(&mreq.imr_address, optval,
+			if (optlen >= sizeof(struct ip_mreq)) {
+				if (copy_from_user(&mreq, optval,
+						   sizeof(struct ip_mreq)))
+					break;
+			} else if (optlen >= sizeof(struct in_addr)) {
+				if (copy_from_user(&mreq.imr_address, optval,
 						   sizeof(struct in_addr)))
 					break;
 			}
+		}
 
 		if (!mreq.imr_ifindex) {
 			if (mreq.imr_address.s_addr == htonl(INADDR_ANY)) {