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代码： 全选

$ man gcc
......
       -fstack-protector
           Emit extra code to check for buffer overflows, such as
           stack smashing attacks.  This is done by adding a guard
           variable to functions with vulnerable objects.  This
           includes functions that call alloca, and functions with
           buffers larger than 8 bytes.  The guards are initialized
           when a function is entered and then checked when the func‐
           tion exits.  If a guard check fails, an error message is
           printed and the program exits.

           NOTE: In Ubuntu 6.10 and 7.04 this option is enabled by
           default for C, C++, ObjC, ObjC++.
......

代码： 全选

$ cat test.c
#include <stdio.h> 
#include <string.h> 

int main(void) {
        char largebuff[]="1234512345123451234512345===ABCD"; 
        char smallbuff[16]; 
        strcpy(smallbuff,largebuff); 
        printf("smallbuff=\"%s\"\n", smallbuff);
        printf("largebuff=\"%s\"\n", largebuff);
}

代码： 全选

$ gcc -g -fno-stack-protector test.c; ./a.out
smallbuff="1234512345123451234512345===ABCD"
largebuff="234512345===ABCD"