9832 Original bug discovered as 9560 has friends IPv4 packets coming in as IPv6 creating chaos

@@ -19,11 +19,11 @@
  * CDDL HEADER END
  */
 /*
  * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
  * Use is subject to license terms.
- * Copyright 2017 Joyent, Inc.
+ * Copyright 2018 Joyent, Inc.
  * Copyright 2013 Nexenta Systems, Inc. All rights reserved.
  */
 
 /*
  * MAC data path

@@ -1787,15 +1787,12 @@
                 /*
                  * Do src based fanout if below tunable is set to B_TRUE or
                  * when mac_ip_hdr_length_v6() fails because of malformed
                  * packets or because mblks need to be concatenated using
                  * pullupmsg().
-                 *
-                 * Perform a version check to prevent parsing weirdness...
                  */
-                if (IPH_HDR_VERSION(ip6h) != IPV6_VERSION ||
-                    !mac_ip_hdr_length_v6(ip6h, mp->b_wptr, &hdr_len, &nexthdr,
+                if (!mac_ip_hdr_length_v6(ip6h, mp->b_wptr, &hdr_len, &nexthdr,
                     NULL)) {
                         goto src_dst_based_fanout;
                 }
         } else {
                 hdr_len = IPH_HDR_LENGTH(ipha);