bad pointer

#include <iostream>
#include <stdlib.h>

struct qnode {
    int value;
    qnode* next;
};

void insertNode(qnode*& ntop, qnode* newNode) {
    if(ntop == NULL) {
        ntop = newNode;
    } else {
        newNode->next = ntop;
        ntop = newNode;
    }
}

void visit(qnode* ntop) {
    if (ntop == NULL) {
        std::cout<<"end queue.";
    } else {
        std::cout<<ntop->value<<"->";
        visit(ntop->next);
    }
}

int main() {
    
    qnode* mqueue = new qnode;
    mqueue->value = 12;
    qnode* inode = new qnode;
    inode->value = 34;
    insertNode(mqueue, inode);
    visit(mqueue);
    delete inode;
    delete mqueue;

    return 0;
}