为什么我的链表的复制构造函数总是出现分段错误

此函数是链表的复制构造。代码在第一个while循环中的某个地方中止，它只是制作新的链表，不确定是什么原因导致的，任何帮助都会受到赞赏。如果你还需要什么，请告诉我。谢谢

DLL::DLL(DLL& n) {
    if (n.headPtr == NULL) {
        headPtr = NULL;
    }
    else {
        //keeps track of the last node in the list                                                        
        Node* lastNode = NULL;
        //keeps track of old list                                                                         
        Node* oldListNode = n.headPtr;
        while (oldListNode != NULL) {
            //create a new Node for new list until reaches end of old list                               
            Node* newNode = new Node;
            newNode->pred = NULL;
            newNode->succ = NULL;
            newNode->ssn = oldListNode->ssn;
            newNode->name = oldListNode->name;
            //add newNode to new List                                                                    
            if (headPtr == NULL) { //new list is empty                                                     
                headPtr = newNode;
                lastNode = headPtr;
            }
            else {
                //adds new node to the end of the list                                                     
                lastNode->succ = newNode;
                newNode->pred = lastNode;
                lastNode = newNode;
            }
            //Goes to the next node in the old list;                                                     
            oldListNode = oldListNode->succ;
        }
    }
    //now puts all information from old list into new list                                              
    itemCount = n.itemCount;
    if (n.headPtr == NULL) {
        headPtr = NULL;
    }
    else {
        if (n.itemCount > 0) {
            cout << "in while loop, ";
            Node *origList = n.headPtr; //pointer accessing old node's data                    
            Node *secondHeadPtr = new Node; //second hptr for new ll                           
            Node *currNode = secondHeadPtr; // points to second ll node that will be filled    
            Node *nextNode; //going to point to added node                                     
            while (currNode != NULL) {
                cout << "in while loop, ";
                nextNode = new Node; //next node, currnode to point to                           
                currNode->ssn = origList->ssn;
                currNode->name = origList->name;
                currNode->succ = nextNode; //create beginning of second ll, next node           
                nextNode->pred = currNode;
                currNode = currNode->succ;
                origList = origList->succ;
                cout << currNode->name << " " << currNode->ssn << " ";
            }
        }
    }
}

头文件

#include <string>
using namespace std;
struct Node {
    string ssn;
    string name;
    Node* succ;
    Node* pred;
};
class DLL {
private:
    Node* headPtr;
    int itemCount;
public:
    DLL();
    DLL(DLL& n);
    virtual ~DLL();
    Node* getHeadPtr();
    int search(string ss) const;
    bool insert(string ss, string name, int & count);
    bool remove(string ss, int & count);
    int size();
    void display();
};

测试文件

#include "DLL.h"
#include <iostream>
#include <string>
using namespace std;
int main() {
    DLL myList;
    int counter = 0;
    int dCounter = 0;
    myList.insert("30", "Jack Eblin", counter);
    myList.insert("40", "Liz Smith", counter);
    myList.insert("10", "Mike Dutter", counter);
    myList.insert("20", "Kitty Lekberg", counter);
    myList.insert("50", "Carma Meshew", counter);
    cout << "After insertion, we should have 10 20 30 40 50 in order" << endl;
    myList.display();
    cout << "Searching 30 in the list, result should be 2" << endl;
    cout << myList.search("30") << endl;
    myList.remove("10", dCounter);
    myList.remove("50", dCounter);
    cout << "After deletion, we should have 20 30 40 in order" << endl;
    myList.display();

    cout << "Testing copy constructor" << endl;
    DLL* temp = new DLL(myList);
    cout << "Contents of the original list" << endl;
    myList.display();
    cout << "Contents of the new list, the memory address of the this list must be different from the
     original list" << endl;
    if (myList.getHeadPtr() != nullptr) {
        temp->display();
    }
    return 0;
}