fix: malloc checks at msc_tree

Author: wooffie

src/utils/msc_tree.cc

@@ -419,6 +419,9 @@ TreeNode *CPTAddElement(unsigned char *ipdata, unsigned int ip_bitmask, CPTTree
                 node->count++;
                 new_node = node;
                 node->netmasks = reinterpret_cast<unsigned char *>(malloc(node->count *  sizeof(unsigned char)));
+                if (node->netmasks == NULL) {
+                    return node;
+                }
                 memset(node->netmasks, 0, (node->count *  sizeof(unsigned char)));
 
                 if ((node->count -1) == 0) {
@@ -491,15 +494,15 @@ TreeNode *CPTAddElement(unsigned char *ipdata, unsigned int ip_bitmask, CPTTree
             }
 
             i_node->netmasks = reinterpret_cast<unsigned char *>(malloc((node->count - i) * sizeof(unsigned char)));
-            memset(i_node->netmasks, 0, ((node->count - i) * sizeof(unsigned char)));
-
             if(i_node->netmasks == NULL) {
                 free(new_node->prefix);
                 free(new_node);
                 free(i_node);
                 return NULL;
             }
 
+            memset(i_node->netmasks, 0, ((node->count - i) * sizeof(unsigned char)));
+
             j = 0;
             while (j < (node->count - i))   {
                 i_node->netmasks[j] = node->netmasks[i + j];