I am having trouble cloning a linked list, what is the problem in my code?

Question

Structure of Node:

class Node{
    public:
    int data;
    Node *next;
    Node *arb;
    Node(int value){
        data=value;
        next=NULL;
        arb=NULL;
    }
};

Now, I wrote the following code, but I am getting a segmentation fault runtime error. I can't find out what is causing this error.

Node *copyList(Node *head)
    {
        Node* ptr=head;
        Node *temp;
        Node *clonehead; 
        Node *clonetail;
        while(ptr!=NULL){
            temp=ptr->next;
            Node* newnode=new Node(ptr->data);
            if(ptr==head){
                clonehead=newnode;
                clonetail=clonehead;
            }
            else{
                clonetail->next=newnode;
                clonetail=newnode;
            }
            clonetail->arb=ptr->arb;
            ptr->next=clonetail;
            ptr=temp;
        }
        ptr=clonehead;
        while(ptr!=NULL){
            temp=ptr->arb;
            ptr->arb=temp->next;
            ptr=ptr->next;
        }
        return clonehead;
    }

What is wrong with my code?

Link to the problem: Clone a linked list with next and random pointer