android13/frameworks/av/media/libaudioclient/fuzzer

Fuzzer for libaudioflinger

Plugin Design Considerations

The fuzzer plugin for libaudioflinger is designed based on the understanding of the library 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. The fuzzer covers libaudioflinger APIs as called from libaudioclient through IPC.

libaudioflinger supports the following parameters:

1. Unique IDs (parameter name: uniqueId)
2. Audio Mode (parameter name: mode)
3. Session ID (parameter name: sessionId)
4. Encapsulation Mode (parameter name: encapsulationMode)
5. Audio Port Role (parameter name: portRole)
6. Audio Port Type (parameter name: portType)
7. Audio Stream Type (parameter name: streamType)
8. Audio Format (parameter name: format)
9. Audio Channel Mask (parameter name: channelMask)
10. Usage (parameter name: usage)
11. Audio Content Type (parameter name: contentType)
12. Input Source (parameter name: inputSource)
13. Input Flags (parameter name: inputFlags)
14. Output Flags (parameter name: outputFlags)
15. Audio Gain Mode (parameter name: gainMode)
16. Audio Device (parameter name: device)

Parameter	Valid Values	Configured Value
uniqueId	0. AUDIO_UNIQUE_ID_USE_UNSPECIFIED 1. AUDIO_UNIQUE_ID_USE_SESSION 2. AUDIO_UNIQUE_ID_USE_MODULE 3. AUDIO_UNIQUE_ID_USE_EFFECT 4. AUDIO_UNIQUE_ID_USE_PATCH 5. AUDIO_UNIQUE_ID_USE_OUTPUT 6. AUDIO_UNIQUE_ID_USE_INPUT 7. AUDIO_UNIQUE_ID_USE_CLIENT 8. AUDIO_UNIQUE_ID_USE_MAX	Value obtained from FuzzedDataProvider
mode	0.AUDIO_MODE_INVALID 1. AUDIO_MODE_CURRENT 2. AUDIO_MODE_NORMAL 3. AUDIO_MODE_RINGTONE 4. AUDIO_MODE_IN_CALL 5. AUDIO_MODE_IN_COMMUNICATION 6. AUDIO_MODE_CALL_SCREEN	Value obtained from FuzzedDataProvider
sessionId	0. AUDIO_SESSION_NONE 1. AUDIO_SESSION_OUTPUT_STAGE 2. AUDIO_SESSION_DEVICE	Value obtained from FuzzedDataProvider
encapsulationMode	0. AUDIO_ENCAPSULATION_MODE_NONE 1. AUDIO_ENCAPSULATION_MODE_ELEMENTARY_STREAM 2. AUDIO_ENCAPSULATION_MODE_HANDLE	Value obtained from FuzzedDataProvider
portRole	0. AUDIO_PORT_ROLE_NONE 1. AUDIO_PORT_ROLE_SOURCE 2. AUDIO_PORT_ROLE_SINK	Value obtained from FuzzedDataProvider
portType	0. AUDIO_PORT_TYPE_NONE 1. AUDIO_PORT_TYPE_DEVICE 2. AUDIO_PORT_TYPE_MIX 3. AUDIO_PORT_TYPE_SESSION	Value obtained from FuzzedDataProvider
streamType	15 values of type audio_stream_type_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
format	77 values of type audio_format_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
channelMask	83 values of type audio_channel_mask_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
usage	22 values of type audio_usage_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
contentType	5 values of type audio_content_type_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
inputSource	14 values of type audio_source_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
inputFlags	9 values of type audio_input_flags_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
outputFlags	16 values of type audio_output_flags_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
gainMode	3 values of type audio_gain_mode_t	Value chosen from valid values by obtaining index from FuzzedDataProvider
device	66 values of type audio_devices_t	Value chosen from valid values by obtaining index from FuzzedDataProvider

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

Maximize utilization of input data

The plugin tolerates any kind of input (empty, huge, malformed, etc) and doesn't exit() on any input and thereby increasing the chance of identifying vulnerabilities.

Build

This describes steps to build audioflinger_fuzzer binary.

Android

Steps to build

Build the fuzzer

  $ mm -j$(nproc) audioflinger_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/audioflinger_fuzzer/audioflinger_fuzzer CORPUS_DIR

References:

• http://llvm.org/docs/LibFuzzer.html
• https://github.co