汇编系统调用无效 [英] assembly system call non-effective

问题描述

我想用以下内容打印 AAAA:

I want to print AAAA with the following:

BITS 32;

;write;
 push 0x41414141;
 pop ecx        ;
 mov eax, 4     ; write is syscall 4 for Ubuntu 32-bit
 mov ebx, 1     ; stdout
 mov edx, 4     ;
 int 0x80       ;

;exit;
 mov eax, 1     ;
 mov ebx, 0     ;
 int 0x80       ;

然而，一旦组装和链接此代码只退出，没有错误，有什么问题?

Yet, once assembled and linked this code only exits, no errors, what is wrong ?

推荐答案

快速修复您的代码:

push 0x41414141 ; put 'AAAA' into stack memory
mov ecx,esp     ; pointer to the 'AAAA'
mov eax, 4      ; write is syscall 4 for 32-bit Linux
mov ebx, 1      ; stdout
mov edx, 4
int 0x80
add esp,4      ; restore stack

没有解释，因为你应该首先检查我在评论中提出的问题，然后修复将是显而易见的，或者你将不得不询问一些你不理解的特定问题......

No explanation, as you should first check what I did ask in comment, then the fix will be either obvious, or you will have to ask about something particular you don't understand...

如果您使用 strace ./my_program 运行原始代码，您会看到 write() 返回 -EFAULT，因为您传递了一个错误地址.始终使用 strace 来调试进行系统调用且行为不符合预期的程序.

If you run your original code with strace ./my_program, you'd see write() return -EFAULT because you passed a bad address. Always use strace to debug programs that make syscalls and don't behave the way you expected.

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