使用C语言编写插入二叉查找树的函数时，出现指针越界的问题，求解

此函数用于插入结点到二叉查找树中， 首次插入2时并未报错，第二次插入时出现断点。

#include <stdio.h>
#include <string.h>
struct TreeNode {
    int data;
    struct TreeNode* left;
    struct TreeNode* right;
};
typedef struct TreeNode SearchNode;

SearchNode* Insert(SearchNode*, int);//插入结点
int main()
{
    SearchNode* root = NULL;
    root = Insert(root, 2);
    root = Insert(root, 1);
    root = Insert(root, 3);

    return 0;
}
SearchNode* Insert(SearchNode* tree, int data)//插入结点
{

    if (tree == NULL)
    {
        SearchNode* tree = (SearchNode*)malloc(sizeof(SearchNode*));
        tree->data = data;
        tree->left = NULL;
        tree->right = NULL;
        return tree;
    }
    else if (tree->data > data)
    {
        Insert(tree->left, data);
        return tree;
    }
    else if(tree->data<data)
    {
        Insert(tree->right,data);
        return tree;
    }
    printf("此节点已存在！");
    return tree;
}

我的解答思路和尝试过的方法

我想要达到的结果