Debugging C Linked List Program caught in infinite loop

Debugging C Linked List Program caught in infinite loop

So this is a very simple program to create and display a linked list. Here
I'm getting caught in the display loop, and I'm seeing infinite
'2->2->2->...' on screen.
After debugging, I can see that my program ALWAYS goes into the if
statement of insertNode() whereas it should only go there ONCE i.e. when
the linked list is initialized.
#include <stdio.h>
#include <stdlib.h>
struct node {
int data;
struct node * next;
};
struct node * head = NULL;
struct node * curr = NULL;
void insertNode(struct node * temp2) {
if (head == NULL) {
head = temp2;
head->next = NULL;
}
else {
temp2->next = head;
head = temp2;
}
}
void display() {
curr = head;
while (curr->next != NULL)
{
printf("%d->",curr->data);
curr = curr->next;
}
}
void main() {
struct node * temp = (struct node *) malloc (sizeof(struct node));
temp->data = 5;
insertNode(temp);
temp->data = 6;
insertNode(temp);
temp->data = 1;
insertNode(temp);
temp->data = 2;
insertNode(temp);
display();
}