Added media_log_fuzzer

cc_fuzz {

    name: "media_log_fuzzer",

    static_libs: [

        "libmedialogservice",

    ],

    srcs: [

        "media_log_fuzzer.cpp",

    ],

    header_libs: [

        "libmedia_headers",

    ],

    shared_libs: [

        "libaudioutils",

        "libbinder",

        "liblog",

        "libmediautils",

        "libnblog",

        "libutils",

    ],

    include_dirs: [

        "frameworks/av/services/medialog",

    ],

    cflags: [

        "-Werror",

        "-Wall",

    ],

    fuzz_config: {

        cc: [

            "android-media-fuzzing-reports@google.com",

        ],

        componentid: 155276,

    },

}

# Fuzzer for libmedialogservice

## Plugin Design Considerations

The fuzzer plugin for libmedialogservice is designed based on the understanding of the

service and tries to achieve the following:

##### Maximize code coverage

The configuration parameters are not hardcoded, but instead selected based on

incoming data. This ensures more code paths are reached by the fuzzer.

medialogservice supports the following parameters:

1. Writer name (parameter name: `writerNameIdx`)

2. Log size (parameter name: `logSize`)

3. Enable dump before unrgister API (parameter name: `shouldDumpBeforeUnregister`)

5. size of string for log dump (parameter name: `numberOfLines`)

| Parameter| Valid Values| Configured Value|

|------------- |-------------| ----- |

| `writerNameIdx` | 0. `0` 1. `1` | Value obtained from FuzzedDataProvider |

| `logSize` | In the range `256 to 65536` | Value obtained from FuzzedDataProvider |

| `shouldDumpBeforeUnregister` | 0. `0` 1. `1` | Value obtained from FuzzedDataProvider |

| `numberOfLines` | In the range `0 to 65535` | Value obtained from FuzzedDataProvider |

This also ensures that the plugin is always deterministic for any given input.

## Build

This describes steps to build media_log_fuzzer binary.

### Android

#### Steps to build

Build the fuzzer

```

  $ mm -j$(nproc) media_log_fuzzer

```

#### Steps to run

Create a directory CORPUS_DIR and copy some files to that folder

Push this directory to device.

To run on device

```

  $ adb sync data

  $ adb shell /data/fuzz/arm64/media_log_fuzzer/media_log_fuzzer CORPUS_DIR

```

## References:

 * http://llvm.org/docs/LibFuzzer.html

 * https://github.com/google/oss-fuzz

/**

 * Copyright (C) 2020 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.

 */

#include <binder/IMemory.h>

#include <binder/MemoryDealer.h>

#include <private/android_filesystem_config.h>

#include "MediaLogService.h"

#include "fuzzer/FuzzedDataProvider.h"

constexpr const char* kWriterNames[2] = {"FastMixer", "FastCapture"};

constexpr size_t kMinSize = 0x100;

constexpr size_t kMaxSize = 0x10000;

constexpr size_t kLogMemorySize = 400 * 1024;

constexpr size_t kMaxNumLines = USHRT_MAX;

using namespace android;

class MediaLogFuzzer {

   public:

    void init();

    void process(const uint8_t* data, size_t size);

   private:

    sp<MemoryDealer> mMemoryDealer = nullptr;

    sp<MediaLogService> mService = nullptr;

};

void MediaLogFuzzer::init() {

    setuid(AID_MEDIA);

    mService = new MediaLogService();

    mMemoryDealer = new MemoryDealer(kLogMemorySize, "MediaLogFuzzer", MemoryHeapBase::READ_ONLY);

}

void MediaLogFuzzer::process(const uint8_t* data, size_t size) {

    FuzzedDataProvider fuzzedDataProvider(data, size);

    size_t writerNameIdx =

        fuzzedDataProvider.ConsumeIntegralInRange<size_t>(0, std::size(kWriterNames) - 1);

    bool shouldDumpBeforeUnregister = fuzzedDataProvider.ConsumeBool();

    size_t logSize = fuzzedDataProvider.ConsumeIntegralInRange<size_t>(kMinSize, kMaxSize);

    sp<IMemory> logBuffer = mMemoryDealer->allocate(NBLog::Timeline::sharedSize(logSize));

    Vector<String16> args;

    size_t numberOfLines = fuzzedDataProvider.ConsumeIntegralInRange<size_t>(0, kMaxNumLines);

    for (size_t lineIdx = 0; lineIdx < numberOfLines; ++lineIdx) {

        args.add(static_cast<String16>(fuzzedDataProvider.ConsumeRandomLengthString().c_str()));

    }

    const char* fileName = "logDumpFile";

    int fd = memfd_create(fileName, MFD_ALLOW_SEALING);

    fuzzedDataProvider.ConsumeData(logBuffer->unsecurePointer(), logBuffer->size());

    mService->registerWriter(logBuffer, logSize, kWriterNames[writerNameIdx]);

    if (shouldDumpBeforeUnregister) {

        mService->dump(fd, args);

        mService->unregisterWriter(logBuffer);

    } else {

        mService->unregisterWriter(logBuffer);

        mService->dump(fd, args);

    }

}

extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {

    MediaLogFuzzer mediaLogFuzzer = MediaLogFuzzer();

    mediaLogFuzzer.init();

    mediaLogFuzzer.process(data, size);

    return 0;

}