C语言错误： HEAP CORRUPTION DETECTED

程序源代码：

//写文件两种方式(文本文件和二进制文件)#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<stdlib.h>
#include<string.h>//文本写文件
int writeWord(const char *path,const char *pword){int ERRO_MSG = 0;if (path == NULL){ERRO_MSG = 1;printf("path==NULL erro msg:%d\n", ERRO_MSG);return ERRO_MSG;}if (pword == NULL){ERRO_MSG = 2;printf("pword==NULL erro msg:%d\n", ERRO_MSG);return ERRO_MSG;}//定义文件指针FILE *fpw=NULL;//打开文件fpw = fopen(path, "w");//w 打开只写文件，若文件存在，则文件长度清零，即文件内容会消失，若文件不存在则建立该文件//判断文件是否打开成功if (fpw==NULL){ERRO_MSG = 1;printf("文件打开失败 fpw==NULL erro msg:%d\n", ERRO_MSG);return ERRO_MSG;}//开始写文件
    fputs(pword, fpw);//关闭文件if (fpw!=NULL){fclose(fpw);}return ERRO_MSG;
}//文件读文件
char ** readtxt(const char *path)//二级指针做输出
{int ERRO_MSG = 0;if (path==NULL){ERRO_MSG = 1;printf("path==NULL erro msg:%d\n", ERRO_MSG);//return ERRO_MSG;
    }//定义文件指针FILE *pfr = NULL;//打开文件pfr = fopen(path, "r");if (pfr==NULL){ERRO_MSG = 3;printf("pfr==NULL erro msg:%d,文件路径：%s\n", ERRO_MSG, path);//return ERRO_MSG;
    }//开始读文件//1.定义文件缓存数组char bufarr[100] = { 0 };//2.0 获取文本具体行数//2.1 定义临时变量int index = 0;//2.0定义返回二维数组char **resbuf = (char **)malloc(sizeof(char *)*5);//读文件while (!feof(pfr)){//feof()如果文件结束，则返回非0值，否则返回0memset(bufarr, 0, sizeof(char));fgets(bufarr, 100, pfr);char *bufstr1 = (char *)malloc(sizeof(char)*strlen(bufarr));//拷贝字符串
        strcpy(bufstr1, bufarr);resbuf[index] = bufstr1;index++;//resbuf = (char **)realloc(resbuf, sizeof(char *)*(index + 2));
    }resbuf[index] = NULL;return resbuf;
}void main(){//定义文件路径char *path = "E:\\Test\\CwordTest\\";//只适用于windowchar *path1 = "E:/Test/CwordTest/a1.txt";//writeWord(path1, "asfasdfasdgafdsgadf\r\n打倒日本帝国主义和所对符合大家的哟撒\r\ndsafgshfetgrhet");char **pdata = NULL;pdata=readtxt(path1);int index = 0;if (pdata!=NULL){while (pdata[index] != NULL){printf("%s\n", pdata[index]);//释放内存free(pdata[index]);pdata[index] = NULL;index++;}free(pdata);pdata = NULL;}system("pause");
}