Add printf NULL checks to silence static analyzer

Add NULL checks to take care of issues reported by static analyzer tool
on potentially using NULL with printf format %s (which has undefined
behavior even though many compilers end up printing "(null)").

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

hostapd/hostapd_cli.c

@@ -844,6 +844,8 @@ static int hostapd_cli_cmd_interface(struct wpa_ctrl *ctrl, int argc,
 	hostapd_cli_close_connection();
 	os_free(ctrl_ifname);
 	ctrl_ifname = os_strdup(argv[0]);
+	if (ctrl_ifname == NULL)
+		return -1;
 
 	if (hostapd_cli_open_connection(ctrl_ifname)) {
 		printf("Connected to interface '%s.\n", ctrl_ifname);

hostapd/main.c

@@ -97,14 +97,15 @@ static void hostapd_logger_cb(void *ctx, const u8 *addr, unsigned int module,
 	else if (hapd && hapd->conf)
 		os_snprintf(format, maxlen, "%s:%s%s %s",
 			    hapd->conf->iface, module_str ? " " : "",
-			    module_str, txt);
+			    module_str ? module_str : "", txt);
 	else if (addr)
 		os_snprintf(format, maxlen, "STA " MACSTR "%s%s: %s",
 			    MAC2STR(addr), module_str ? " " : "",
-			    module_str, txt);
+			    module_str ? module_str : "", txt);
 	else
 		os_snprintf(format, maxlen, "%s%s%s",
-			    module_str, module_str ? ": " : "", txt);
+			    module_str ? module_str : "",
+			    module_str ? ": " : "", txt);
 
 	if ((conf_stdout & module) && level >= conf_stdout_level) {
 		wpa_debug_print_timestamp();