这边遇见了“间接寻址级别不同的问题”

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#include<time.h>
#include<string.h>

typedef struct ListNode* ptr;
struct ListNode {
    int val;
    struct ListNode* next;
};

void ReverseList(struct ListNode* L)
{
    ptr p = findptr(L);
    ptr head = L;
    while (p != head)
    {
        //反转
        p->next->next = p;
        p->next = NULL;
        //更新p
        p = findptr(L), head = L;
    }
    if (head->next != NULL) {
        p->next->next = p;
        p->next = NULL;
    }
    /////////////////////////////
}

struct ListNode* findptr(struct ListNode* L)
{
    ptr head = L;
    ptr p = head, temp = p;
    if (p->next != NULL) temp = p->next;
    //找最后
    while (temp->next != NULL)
    {
        p = p->next;
        temp = p->next;
    }
    return p;
}

int main() {
    //
    ptr l1;
    //l1
    ptr p = malloc(sizeof(struct ListNode)), temp = NULL;
    l1 = p;
    if (p == NULL) {
        return 1;
    }
    p->val = 2;
    temp = malloc(sizeof(struct ListNode));
    if (temp == NULL) {
        return 1;
    }
    temp->val = 4;
    p->next = temp;
    temp->next = NULL;
    ////
    ReverseList(l1);
    p = findptr(l1);
    printf("%d ",p->next->val );
    return 0;
}