Revert "Fix for CVE-2018-13441 null pointer dereference (#553)"

This reverts commit c399086.

Author: hedenface

Changelog

@@ -7,7 +7,6 @@ Nagios Core 4 Change Log
 * Fix for duplicate comments on reload (#549) (Bryan Heden)
 * Fix for check_interval/retry_interval bug (Scott Wilkerson)
 * Fix passive checks sending recovery email when host was previously up (Scott Wilkerson)
-* Fix for CVE-2018-13441 null pointer dereference (Trevor McDonald)
 
 4.4.1 - 2018-06-25
 ------------------

base/query-handler.c

@@ -26,7 +26,7 @@ static int qh_echo(int sd, char *buf, unsigned int len)
 {
 	int result = 0;
 
-	if (buf == NULL || !strcmp(buf, "help")) {
+	if (!strcmp(buf, "help")) {
 
 		nsock_printf_nul(sd,
 			"Query handler that simply echoes back what you send it.");
@@ -371,7 +371,7 @@ static int qh_help(int sd, char *buf, unsigned int len)
 {
 	struct query_handler *qh = NULL;
 
-	if (buf == NULL || !strcmp(buf, "help")) {
+	if (!*buf || !strcmp(buf, "help")) {
 		nsock_printf_nul(sd,
 			"  help <name>   show help for handler <name>\n"
 			"  help list     list registered handlers\n");
@@ -405,7 +405,7 @@ static int qh_core(int sd, char *buf, unsigned int len)
 {
 	char *space;
 
-	if (buf == NULL || !strcmp(buf, "help")) {
+	if (*buf == 0 || !strcmp(buf, "help")) {
 
 		nsock_printf_nul(sd, 
 			"Query handler for manipulating nagios core.\n"