ofp-port: Free memory on error in ofp_print_ofpst_port_reply

Counters in ops->custom_stats may already be valid at this error point.
This patch frees the leaked memory.

Reported-at: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=10322
Signed-off-by: Yifeng Sun <pkusunyifeng@gmail.com>
Signed-off-by: Ben Pfaff <blp@ovn.org>

lib/ofp-port.c

@@ -1679,6 +1679,7 @@ ofputil_pull_ofp14_port_stats(struct ofputil_port_stats *ops,
 
         error = ofpprop_pull(&properties, &payload, &type);
         if (error) {
+            netdev_free_custom_stats_counters(&ops->custom_stats);
             return error;
         }
         switch (type) {