From 83f66de6edb31b34776dde714dfb9e8f01ad2a34 Mon Sep 17 00:00:00 2001
From: Franco Fichtner <franco@opnsense.org>
Date: Sun, 9 Dec 2018 06:20:36 +0100
Subject: [PATCH] system: protect mac call

---
 src/www/system_advanced_network.php | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/www/system_advanced_network.php b/src/www/system_advanced_network.php
index f46a50128..045bf9d3c 100644
--- a/src/www/system_advanced_network.php
+++ b/src/www/system_advanced_network.php
@@ -37,9 +37,11 @@ require_once("system.inc");
 function get_mac_address()
 {
     $ip = getenv('REMOTE_ADDR');
-    $mac = `/usr/sbin/arp -an | grep {$ip} | cut -d" " -f4`;
-    $mac = str_replace("\n","",$mac);
-    return $mac;
+    $macs = array();
+
+    exec(exec_safe('/usr/sbin/arp -an | grep %s | awk \'{ print $4 }\'', $ip), $macs);
+
+    return !empty($macs[0]) ? $macs[0] : '';
 }
 
 function generate_new_duid($duid_type)