leetcode - Add Two Numbers

struct ListNode* addTwoNumbers(struct ListNode* l1, struct ListNode* l2) {
    struct ListNode* l3 = malloc(sizeof(struct ListNode));
    struct ListNode* l4 = l3;

    l3->val = 0;
    l3->next = NULL;

    while(l1 != NULL && l2 != NULL) {
        int wholeP = (l1->val + l2->val + l3->val) / 10;

        l3->val = (l1->val + l2->val + l3->val) % 10;
        if(l1->next != NULL || l2->next != NULL || wholeP > 0) {
            l3->next = malloc(sizeof(struct ListNode));
            l3->next->val = wholeP;
            l3 = l3->next;
        }

        l1 = l1->next;
        l2 = l2->next;
    }

    while(l1 != NULL) {
        int wholeP = (l1->val + l3->val) / 10;

        l3->val = (l1->val + l3->val) % 10;
        if(l1->next != NULL || wholeP > 0) {
            l3->next = malloc(sizeof(struct ListNode));
            l3->next->val = wholeP;
            l3 = l3->next;
        }
        l1 = l1->next;
    }
    while(l2 != NULL) {
        int wholeP = (l2->val + l3->val) / 10;

        l3->val = (l2->val + l3->val) % 10;
        if(l2->next != NULL || wholeP > 0) {
            l3->next = malloc(sizeof(struct ListNode));
            l3->next->val = wholeP;
            l3 = l3->next;
        }
        l2 = l2->next;
    }
    l3->next = NULL;

    return l4;
}