Get the middle node in a given singly linked list?

struct node
{
   int info;
   struct node *next;
};

struct node* getMiddleNode(struct node **start)

{

  struct node *middle = *start;

  struct node *fast_ptr = *start;

  if(*start != NULL)

  {

       while((fast_ptr->next) !=NULL && (fast_ptr->next->next) != NULL)

       {

          fast_ptr = fast_ptr->next->next;

          middle = middle->next;

       }

  }

   return middle ;

}