// compile with: /c /W1 #include <cstring> #include <stdlib.h> #pragma warning(disable : 4996) // for strcpy use // Vulnerable function void vulnerable(const char *str) { char buffer[10]; strcpy(buffer, str); // overrun buffer !!! // use a secure CRT function to help prevent buffer overruns // truncate string to fit a 10 byte buffer // strncpy_s(buffer, _countof(buffer), str, _TRUNCATE); } int main() { // declare buffer that is bigger than expected char large_buffer[] = "This string is longer than 10 characters!!"; vulnerable(large_buffer); }

这段代码存在一个缓冲区溢出漏洞，即在函数`vulnerable`中调用`strcpy`将`str`拷贝到长度为10的缓冲区`buffer`中，如果`str`的长度超过10，就会导致缓冲区溢出，覆盖掉`buffer`后面的内存区域，可能导致程序崩溃或者恶意攻击者执行任意代码。同时，这段代码也存在其他问题，如使用了不安全的C函数`strcpy`，可以被替换成更安全的函数`strncpy_s`等。建议在代码中使用更加安全的C函数，如`strncpy_s`，并对输入进行长度和边界的检查。

相关问题

当你输入很长的字符串时，会出现缓冲区溢出，在把name覆盖掉的同时，并且会更改gold的值为你的字符串后四位，请修改以下代码来实现：// savegame.c // Compile using gcc -fno-stack-protector savegame.c #include <stdio.h> #include <stdlib.h> #include <string.h> struct hero { unsigned int hp; char name[10]; unsigned int gold; }; void secret_function() { printf("You made it!\n"); return; } struct hero setup_hero() { struct hero h; h.hp = 30; h.gold = 8; scanf("%s", h.name); return h; } int main(int argc, const char *argv[]) { struct hero h = setup_hero(); printf("Name: %s\n", h.name); printf("HP: %d | Gold: %d\n", h.hp, h.gold); return 0; }

为了避免缓冲区溢出，可以使用 fgets() 函数代替 scanf() 函数读取输入。此外，可以使用 strncpy() 函数来复制字符串，以确保不会溢出。修改后的代码如下：

// savegame.c
// Compile using gcc -fno-stack-protector savegame.c

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

struct hero {
    unsigned int hp;
    char name[10];
    unsigned int gold;
};

void secret_function() {
    printf("You made it!\n");
    return;
}

struct hero setup_hero() {
    struct hero h;
    h.hp = 30;
    h.gold = 8;
    fgets(h.name, 10, stdin);
    h.name[strcspn(h.name, "\n")] = '\0'; // Remove newline character from input
    strncpy(&h.gold, &h.name[strlen(h.name) - 4], 4); // Copy last 4 characters of input into gold
    return h;
}

int main(int argc, const char *argv[]) {
    struct hero h = setup_hero();
    printf("Name: %s\n", h.name);
    printf("HP: %d | Gold: %d\n", h.hp, h.gold);
    return 0;
}

在新的代码中，我们使用 fgets() 函数读取输入，并且使用 strcspn() 函数来删除输入中的换行符。然后，我们使用 strncpy() 函数将输入的最后四个字符复制到 gold 字段中。这样，即使输入的字符串很长，也不会溢出缓冲区。

windows golang ./opencv.h:10:10: fatal error: opencv/cv.h: No such file or directory

This error indicates that the compiler is unable to find the header file "opencv/cv.h" which is required for the program to compile successfully.

To resolve this error, you need to ensure that you have installed the OpenCV library and have included the correct path to the header files in your code.

Here are the steps to fix this error:

1. Install OpenCV library on your system. You can download the latest version of OpenCV from the official website (https://opencv.org/releases/).

2. Once you have installed OpenCV, locate the directory where the header files are stored. In most cases, the header files are stored in the "include" directory within the OpenCV installation directory.

3. Update your code to include the correct path to the header files. You can use the following code snippet to include the path to the header files:

#include <opencv2/opencv.hpp>

4. Compile your code again and the error should be resolved.

If you are still facing issues, you can try updating your system's environment variables to include the path to the OpenCV library directory.