彻底毁掉了我的 gcc 编译器。需要帮助使其达到正确的状态

Question

首先，我试图编译这个 c 代码。

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我正在使用开发人员推荐的命令，例如

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gcc 40049.c -m32 -O2 -o decr\n

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并收到此错误

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/usr/include/features.h:323:26: fatal error: bits/predefs.h: No such file or directory\n

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执行此命令后

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sudo apt-get install gcc-multilib\n

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我以为代码可以编译，但我错了。

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运行相同的命令后，我在 Kali Linux 机器的终端中收到了错误的全文，如图所示。

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/bin/bash: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV), dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2\n

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这是我收到的错误的一个片段。

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40049.c: In function \xe2\x80\x98main\xe2\x80\x99:\n40049.c:200:19: warning: incompatible implicit declaration of built-in function \xe2\x80\x98malloc\xe2\x80\x99\n  200 |  stack = (void *) malloc(65536);\n      |                   ^~~~~~\n40049.c:200:19: note: include \xe2\x80\x98<stdlib.h>\xe2\x80\x99 or provide a declaration of \xe2\x80\x98malloc\xe2\x80\x99\n40049.c: At top level:\n40049.c:214:1: error: expected identifier or \xe2\x80\x98(\xe2\x80\x99 before \xe2\x80\x98--\xe2\x80\x99 token\n  214 | --------------------------------------------------- pwn.c ---------------------------------------------------\n      | ^~\n40049.c: In function \xe2\x80\x98privesc\xe2\x80\x99:\n40049.c:240:42: warning: cast from pointer to integer of different size [-Wpointer-to-int-cast]\n  240 |         commit_creds(prepare_kernel_cred((uint64_t)NULL));\n      |                                          ^\n40049.c: At top level:\n40049.c:243:5: error: redefinition of \xe2\x80\x98main\xe2\x80\x99\n  243 | int main() {\n      |     ^~~~\n40049.c:178:5: note: previous definition of \xe2\x80\x98main\xe2\x80\x99 was here\n  178 | int main(void) {\n      |     ^~~~\n40049.c: In function \xe2\x80\x98main\xe2\x80\x99:\n40049.c:249:2: warning: incompatible implicit declaration of built-in function \xe2\x80\x98memset\xe2\x80\x99\n  249 |  memset(shellcode, 0, 0x300000);\n      |  ^~~~~~\n40049.c:249:2: note: include \xe2\x80\x98<string.h>\xe2\x80\x99 or provide a declaration of \xe2\x80\x98memset\xe2\x80\x99\n40049.c:251:14: warning: implicit declaration of function \xe2\x80\x98memcpy\xe2\x80\x99 [-Wimplicit-function-declaration]\n  251 |  void *ret = memcpy(shellcode, &privesc, 0x300);\n      |              ^~~~~~\n40049.c:251:14: warning: incompatible implicit declaration of built-in function \xe2\x80\x98memcpy\xe2\x80\x99\n40049.c:251:14: note: include \xe2\x80\x98<string.h>\xe2\x80\x99 or provide a declaration of \xe2\x80\x98memcpy\xe2\x80\x99\n

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我对此很陌生，所以感谢大家的帮助。

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Answer 1

我还没有测试过它，但该代码旨在分为两个不同的文件：decr.c和pwn.c. 您将其全部保存为40049.c.

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看：

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40049.c:214:1: error: expected identifier or \xe2\x80\x98(\xe2\x80\x99 before \xe2\x80\x98--\xe2\x80\x99 token\n  214 | --------------------------------------------------- pwn.c ---------------------------------------------------\n      | ^~\n

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第 214 行是一个标记，告诉您这是文件的开头pwn.c。此行无效 C.

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另外，你还有这个：

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40049.c:243:5: error: redefinition of \xe2\x80\x98main\xe2\x80\x99\n  243 | int main() {\n      |     ^~~~\n40049.c:178:5: note: previous definition of \xe2\x80\x98main\xe2\x80\x99 was here\n  178 | int main(void) {\n      |     ^~~~\n

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这两个主电源是两个不同可执行文件的一部分。

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