我对编程很陌生,并且一直在研究C。我试图生成一个简单的缓冲区溢出并能够将结果作为练习进行预测,但是在尝试这样做时,甚至无法创建溢出。我正在使用MinGW,它似乎会自动调整数组以适合内容。我正在使用-Wall和-Wextra进行编译,但是没有出现任何错误。这里到底发生了什么?为什么我没有节段错误?我的nNum不应该被改写吗?当我向不应该触摸的地方随机写入内容时,应该不会抱怨吗?谢谢!

#include <stdio.h>
#include <string.h>

/*  Array index - something to be sure that you're outside of szArray  */
#define SZ_LOCATION 15

int main(void)
{
    /*  Initialize array and number.  Store 1000 to number, and "hello\0" to array  */
    char szArray[6];
    unsigned short nNum = 1000;
    strcpy(szArray, "hello");

    printf("SZ_LOCATION = %i\n\n", SZ_LOCATION);

    /*  Print current contents of szArray ("hello").  Print the char at the preset index location, and the current (unchanged) value of nNum  */
    printf("szArray = %s\n", szArray);
    printf("szArray[SZ_LOCATION] = %c\n", szArray[SZ_LOCATION]);
    printf("nNum = %d\n\n", nNum);

    /*  Add 3 chars to szArray, to push it over 6 chars.  Re-print all variables  */
    strcat(szArray, "BIG");
    printf("szArray = %s\t(%I64u bytes)\nszArray[7] = %c\nnNum = %d\n\n", szArray, sizeof(szArray), szArray[sizeof(szArray) + 1], nNum);

    /*  Store a random char to the preset location in the array, way out there, and re-print its contents, with the new size of the array  */
    szArray[SZ_LOCATION] = 'h';
    printf("szArray = %s\nszArray[SZ_LOCATION] = %c\nsizeof(szArray) = %I64u\n", szArray, szArray[SZ_LOCATION], sizeof(szArray));

    return 0;
}

最佳答案

改变这个

/*  Add 3 chars to szArray, to push it over 6 chars.  Re-print all variables  */
strcat(szArray, "BIG");
printf("szArray = %s\t(%I64u bytes)\nszArray[7] = %c\nnNum = %d\n\n", szArray, sizeof(szArray), szArray[sizeof(szArray) + 1], nNum);


成为

while (1)
{
  /*  Add 3 chars to szArray, to push it over 6 chars.  Re-print all variables  */
  strcat(szArray, "BIG");
  printf("szArray = %s\t(%I64u bytes)\nszArray[7] = %c\nnNum = %d\n\n", szArray, sizeof(szArray), szArray[sizeof(szArray) + 1], nNum);
}


并监视程序的输出。

关于c - 自动边界检查?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/21814250/

10-14 18:39
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