pwnable.kr-fd-Writeup

 1 fd@ubuntu:~$ cat fd.c
 2 #include <stdio.h>
 3 #include <stdlib.h>
 4 #include <string.h>
 5 char buf[32];
 6 int main(int argc, char* argv[], char* envp[]){
 7         if(argc<2){
 8                 printf("pass argv[1] a number\n");
 9                 return 0;
10         }
11         int fd = atoi( argv[1] ) - 0x1234;
12         int len = 0;
13         len = read(fd, buf, 32);
14         if(!strcmp("LETMEWIN\n", buf)){
15                 printf("good job :)\n");
16                 system("/bin/cat flag");
17                 exit(0);
18         }
19         printf("learn about Linux file IO\n");
20         return 0;
21 
22 }
23 
24 fd@ubuntu:~$