Untitled

$ gcc -g -o helloworld helloworld.c


gdb -q helloworld
Reading symbols from helloworld...done.
gdb-peda$ disas main
Dump of assembler code for function main:
   0x000000000000063a <+0>: push   rbp
   0x000000000000063b <+1>: mov    rbp,rsp
   0x000000000000063e <+4>: lea    rdi,[rip+0x9f]        # 0x6e4
   0x0000000000000645 <+11>:    call   0x510 <puts@plt>
   0x000000000000064a <+16>:    mov    eax,0x0
   0x000000000000064f <+21>:    pop    rbp
   0x0000000000000650 <+22>:    ret
End of assembler dump.
gdb-peda$ b *(main+11)
Breakpoint 1 at 0x645: file helloworld.c, line 21.
gdb-peda$ r
Starting program: /home/ubuntu/c/helloworld
[----------------------------------registers-----------------------------------]
RAX: 0x55555555463a (<main>:    push   rbp)
RBX: 0x0
RCX: 0x555555554660 (<__libc_csu_init>: push   r15)
RDX: 0x7fffffffe3b8 --> 0x7fffffffe64c ("LANG=en_US.UTF-8")
RSI: 0x7fffffffe3a8 --> 0x7fffffffe619 ("/home/ubuntu/c/helloworld")
RDI: 0x5555555546e4 ("Hello world!")
RBP: 0x7fffffffe2c0 --> 0x555555554660 (<__libc_csu_init>:  push   r15)
RSP: 0x7fffffffe2c0 --> 0x555555554660 (<__libc_csu_init>:  push   r15)
RIP: 0x555555554645 (<main+11>: call   0x555555554510 <puts@plt>)
R8 : 0x7ffff7dd0d80 --> 0x0
R9 : 0x7ffff7dd0d80 --> 0x0
R10: 0x0
R11: 0x1
R12: 0x555555554530 (<_start>:  xor    ebp,ebp)
R13: 0x7fffffffe3a0 --> 0x1
R14: 0x0
R15: 0x0
EFLAGS: 0x246 (carry PARITY adjust ZERO sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x55555555463a <main>:   push   rbp
   0x55555555463b <main+1>: mov    rbp,rsp
   0x55555555463e <main+4>: lea    rdi,[rip+0x9f]        # 0x5555555546e4
=> 0x555555554645 <main+11>:    call   0x555555554510 <puts@plt>
   0x55555555464a <main+16>:    mov    eax,0x0
   0x55555555464f <main+21>:    pop    rbp
   0x555555554650 <main+22>:    ret
   0x555555554651:  nop    WORD PTR cs:[rax+rax*1+0x0]
Guessed arguments:
arg[0]: 0x5555555546e4 ("Hello world!")
[------------------------------------stack-------------------------------------]
0000| 0x7fffffffe2c0 --> 0x555555554660 (<__libc_csu_init>: push   r15)
0008| 0x7fffffffe2c8 --> 0x7ffff7a05b97 (<__libc_start_main+231>:   mov    edi,eax)
0016| 0x7fffffffe2d0 --> 0x1
0024| 0x7fffffffe2d8 --> 0x7fffffffe3a8 --> 0x7fffffffe619 ("/home/ubuntu/c/helloworld")
0032| 0x7fffffffe2e0 --> 0x100008000
0040| 0x7fffffffe2e8 --> 0x55555555463a (<main>:    push   rbp)
0048| 0x7fffffffe2f0 --> 0x0
0056| 0x7fffffffe2f8 --> 0xeb556094de1bb3f8
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value

Breakpoint 1, 0x0000555555554645 in main () at helloworld.c:21
21      printf("Hello world!\n");
gdb-peda$ si
[----------------------------------registers-----------------------------------]
RAX: 0x55555555463a (<main>:    push   rbp)
RBX: 0x0
RCX: 0x555555554660 (<__libc_csu_init>: push   r15)
RDX: 0x7fffffffe3b8 --> 0x7fffffffe64c ("LANG=en_US.UTF-8")
RSI: 0x7fffffffe3a8 --> 0x7fffffffe619 ("/home/ubuntu/c/helloworld")
RDI: 0x5555555546e4 ("Hello world!")
RBP: 0x7fffffffe2c0 --> 0x555555554660 (<__libc_csu_init>:  push   r15)
RSP: 0x7fffffffe2b8 --> 0x55555555464a (<main+16>:  mov    eax,0x0)
RIP: 0x555555554510 (<puts@plt>:    jmp    QWORD PTR [rip+0x200aba]        # 0x555555754fd0)
R8 : 0x7ffff7dd0d80 --> 0x0
R9 : 0x7ffff7dd0d80 --> 0x0
R10: 0x0
R11: 0x1
R12: 0x555555554530 (<_start>:  xor    ebp,ebp)
R13: 0x7fffffffe3a0 --> 0x1
R14: 0x0
R15: 0x0
EFLAGS: 0x246 (carry PARITY adjust ZERO sign trap INTERRUPT direction overflow)
[-------------------------------------code-------------------------------------]
   0x555555554501:  xor    eax,0x200aba
   0x555555554506:  jmp    QWORD PTR [rip+0x200abc]        # 0x555555754fc8
   0x55555555450c:  nop    DWORD PTR [rax+0x0]
=> 0x555555554510 <puts@plt>:   jmp    QWORD PTR [rip+0x200aba]        # 0x555555754fd0
 | 0x555555554516 <puts@plt+6>: push   0x0
 | 0x55555555451b <puts@plt+11>:    jmp    0x555555554500
 | 0x555555554520 <__cxa_finalize@plt>: jmp    QWORD PTR [rip+0x200ad2]        # 0x555555754ff8
 | 0x555555554526 <__cxa_finalize@plt+6>:   xchg   ax,ax
 |->   0x7ffff7a649c0 <_IO_puts>:   push   r13
       0x7ffff7a649c2 <_IO_puts+2>: push   r12
       0x7ffff7a649c4 <_IO_puts+4>: mov    r12,rdi
       0x7ffff7a649c7 <_IO_puts+7>: push   rbp
                                                                  JUMP is taken
[------------------------------------stack-------------------------------------]
0000| 0x7fffffffe2b8 --> 0x55555555464a (<main+16>: mov    eax,0x0)
0008| 0x7fffffffe2c0 --> 0x555555554660 (<__libc_csu_init>: push   r15)
0016| 0x7fffffffe2c8 --> 0x7ffff7a05b97 (<__libc_start_main+231>:   mov    edi,eax)
0024| 0x7fffffffe2d0 --> 0x1
0032| 0x7fffffffe2d8 --> 0x7fffffffe3a8 --> 0x7fffffffe619 ("/home/ubuntu/c/helloworld")
0040| 0x7fffffffe2e0 --> 0x100008000
0048| 0x7fffffffe2e8 --> 0x55555555463a (<main>:    push   rbp)
0056| 0x7fffffffe2f0 --> 0x0
[------------------------------------------------------------------------------]
Legend: code, data, rodata, value
0x0000555555554510 in puts@plt ()
gdb-peda$ x/gx 0x555555754fd0
0x555555754fd0: 0x00007ffff7a649c0
gdb-peda$ x/4i 0x00007ffff7a649c0
   0x7ffff7a649c0 <_IO_puts>:   push   r13
   0x7ffff7a649c2 <_IO_puts+2>: push   r12
   0x7ffff7a649c4 <_IO_puts+4>: mov    r12,rdi
   0x7ffff7a649c7 <_IO_puts+7>: push   rbp