Valgrind显示可能失去记忆

Question

基本上，我正在尝试在C中实现单链表，我正在使用valgrind来检查是否有任何内存泄漏。 Valgrind显示内存泄漏“可能已丢失”，但我释放了堆上的每个malloc，我不确定它在哪里发生。

以下是我的记忆错误图片的链接：http://imgur.com/a/E1Ko0

这是我的代码，输出显示在valgrind图像中。

#include <stdio.h>
#include <stdlib.h>

/* defines node object */
struct node
{
    /* node holds data */
    long data;

    /* next pointer */
    struct node *next;
};


struct node * buildList (void);
long getElement (struct node *, int index);
int lenList(struct node *Head);
void insertList(struct node **Head);
void delete_List (struct node **Head);

/* builds a list of four nodes */
struct node * buildList (void)
{
    struct node * head = (struct node *) malloc(sizeof(struct node));
    struct node * second = (struct node *) malloc(sizeof(struct node));
    struct node * third = (struct node *) malloc(sizeof(struct node));
    struct node * fourth = (struct node *) malloc(sizeof(struct node));
    head ->data = 1;
    head ->next = second;
    second ->data = 2;
    second ->next = third;
    third ->data = 3;
    third ->next = fourth;
    fourth ->data = 4;
    fourth ->next = NULL;

    /* returns pointer to first node*/
    return head;
}

/* gets value at list index */
long getElement(struct node *Head, int index)
{
    for (int i = 0; i<index; i++)
    {
        Head = Head -> next;
    }
    return Head -> data;
}

/* gets length of list */
int lenList(struct node *Head)
{
    int counter = 0;
    while (Head != NULL)
    {
        counter++;
        Head = Head->next;
    }
    return counter;
}

/* inserts node at beginning of list, resets head pointer to new node */
void insertList(struct node **Head)
{
    struct node *newnode = (struct node *) malloc (sizeof(struct node));
    newnode->data = 0;
    newnode->next = *Head;

    /* head pointer now points to first node */
    *Head = newnode;
}

/* deletes and deallocates list memory */
void delete_List (struct node **Head)
{
    struct node *temp;
    struct node *current = *Head;
    while (current!=NULL)
    {
        temp = current;
        current = current -> next;
        free(temp);
    }

    /* mark list as empty */
    *Head = NULL;
}

int main(void)
{
    struct node * headpointer = buildList();
    printf("Initial length of list is: %d\n", lenList(headpointer));
    insertList(&headpointer);
    printf("After inserting node, list length is: %d\n", lenList(headpointer));
    printf("The data at index 1 is: %ld\n", getElement(headpointer, 1));
    delete_List(&headpointer);
    printf("Headpointer should now be equal to null: %x\n", headpointer);
    return 0;
}