Bug#934394:

[ltspro2]

I suggest applying the attached patch.
--- dhcp.c	2019-07-30 00:00:00.000000000 +0000
+++ dhcp.c	2019-08-12 00:00:00.000000000 +0000
@@ -1146,6 +1146,8 @@ int pumpDhcpRelease(struct pumpNetIntf *
 	free(intf->hostname);
     if (intf->set & PUMP_NETINFO_HAS_DOMAIN)
 	free(intf->domain);
+    if (intf->set & PUMP_NETINFO_HAS_NISDOMAIN)
+	free(intf->nisDomain);
 
     syslog(LOG_INFO, "disabling interface %s", intf->device);