Index: head/UPDATING
===================================================================
--- head/UPDATING
+++ head/UPDATING
@@ -32,6 +32,14 @@
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
 20160818:
+	The UDP receive code has been updated to only treat incoming UDP
+	packets that were addressed to an L2 broadcast address as L3
+	broadcast packets.  It is not expected that this will affect any
+	standards-conforming UDP application.  The new behaviour can be
+	disabled by setting the sysctl net.inet.udp.require_l2_bcast to
+	0.
+
+20160818:
 	Remove the openbsd_poll system call.
         __FreeBSD_version has been bumped because of this.
 
Index: head/sys/netinet/udp_usrreq.c
===================================================================
--- head/sys/netinet/udp_usrreq.c
+++ head/sys/netinet/udp_usrreq.c
@@ -126,6 +126,11 @@
     &VNET_NAME(udp_blackhole), 0,
     "Do not send port unreachables for refused connects");
 
+static VNET_DEFINE(int, udp_require_l2_bcast) = 1;
+SYSCTL_INT(_net_inet_udp, OID_AUTO, require_l2_bcast, CTLFLAG_VNET | CTLFLAG_RW,
+    &VNET_NAME(udp_require_l2_bcast), 0,
+    "Only treat packets sent to an L2 broadcast address as broadcast packets");
+
 u_long	udp_sendspace = 9216;		/* really max datagram size */
 SYSCTL_ULONG(_net_inet_udp, UDPCTL_MAXDGRAM, maxdgram, CTLFLAG_RW,
     &udp_sendspace, 0, "Maximum outgoing UDP datagram size");
@@ -523,7 +528,8 @@
 
 	pcbinfo = udp_get_inpcbinfo(proto);
 	if (IN_MULTICAST(ntohl(ip->ip_dst.s_addr)) ||
-	    in_broadcast(ip->ip_dst, ifp)) {
+	    ((!VNET_NAME(udp_require_l2_bcast) || m->m_flags & M_BCAST) &&
+	    in_broadcast(ip->ip_dst, ifp))) {
 		struct inpcb *last;
 		struct inpcbhead *pcblist;
 		struct ip_moptions *imo;