v811_spc009/external/libopus/fuzzer/README.md

Fuzzer for libopus decoder

Plugin Design Considerations

The fuzzer plugin for opus decoder is designed based on the understanding of the codec and tries to achieve the following:

Maximize code coverage

This fuzzer provides support for both single stream and multi stream inputs, thus enabling fuzzing for API's provided for single stream as well as multi stream.

Following arguments are passed to OPUS_DEC_CREATE_API:

1. Sampling frequency (parameter name: Fs)
2. Number of channels (parameter name: channels)

Parameter	Valid Values	Configured Value
Fs	8000 12000 16000 24000 48000	Derived from Byte-9 of input stream
channels	1 2	Derived from Byte-9 of input stream

Maximize utilization of input data

The plugin feeds the entire input data to the codec. Frame sizes are determined only after the call to extractor, so in absence of call to extractor, we feed the entire data to the decoder. This ensures that the plugin tolerates any kind of input (empty, huge, malformed, etc) and doesnt exit() on any input and thereby increasing the chance of identifying vulnerabilities.

Build

This describes steps to build opus_dec_fuzzer and opus_multistream_dec_fuzzer binary.

Android

Steps to build

Build the fuzzer

  $ mm -j$(nproc) opus_dec_fuzzer
  $ mm -j$(nproc) opus_multistream_dec_fuzzer

Steps to run

Create a directory CORPUS_DIR and copy some opus files to that folder. Push this directory to device.

To run on device

  $ adb sync data
  $ adb shell /data/fuzz/arm64/opus_dec_fuzzer/opus_dec_fuzzer CORPUS_DIR
  $ adb shell /data/fuzz/arm64/opus_multistream_dec_fuzzer/opus_multistream_dec_fuzzer CORPUS_DIR

To run on host

  $ $ANDROID_HOST_OUT/fuzz/x86_64/opus_dec_fuzzer/opus_dec_fuzzer CORPUS_DIR
  $ $ANDROID_HOST_OUT/fuzz/x86_64/opus_multistream_dec_fuzzer/opus_multistream_dec_fuzzer CORPUS_DIR

Fuzzer for libopus encoder

Plugin Design Considerations

The fuzzer plugin for opus encoder is designed based on the understanding of the codec and tries to achieve the following:

Maximize code coverage

This fuzzer provides support for both single stream and multi stream inputs, thus enabling fuzzing for API's provided for single stream as well as multi stream. Following arguments are passed to OPUS_ENC_CREATE_API:

1. Sampling rate (parameter name: sampleRate)
2. Number of channels (parameter name: channels)

Parameter	Valid Values	Configured Value
sampleRate	8000 12000 16000 24000 48000	An index ranging from 0-4 is calculated using first byte of data which is used to assign value to sampleRate from array kSampleRates
channels (single stream)	1 2	Calculated using second byte of data
channels (multi stream)	In range 1 - 255	Calculated using second byte of data

Following arguments are passed to OPUS_ENC_CTL_API:

1. OPUS_SET_BITRATE (parameter name: bitRate)
2. OPUS_SET_COMPLEXITY (parameter name: complexity)
3. OPUS_SET_APPLICATION (parameter name: application)
4. OPUS_SET_DTX (parameter name: setDTX)
5. OPUS_SET_SIGNAL (parameter name: signal)
6. OPUS_SET_VBR (parameter name: setVBR)
7. OPUS_SET_VBR_CONSTRAINT (parameter name: setVBRConstraint)
8. OPUS_SET_FORCE_CHANNELS (parameter name: forceChannel)
9. OPUS_SET_MAX_BANDWIDTH (parameter name: maxBandwidth)
10. OPUS_SET_INBAND_FEC (parameter name: setInbandFec)
11. OPUS_SET_PACKET_LOSS_PERC (parameter name: pktLoss)
12. OPUS_SET_LSB_DEPTH (parameter name: lsbDepth)
13. OPUS_SET_PREDICTION_DISABLED (parameter name: setPredDisable)
14. OPUS_SET_EXPERT_FRAME_DURATION (parameter name: frameSizeEnum)

Parameter	Valid Values	Configured Value
bitRate	In range 500 to 512000	Calculated using all bits of 3rd, 4th and 5th byte of data
complexity	0.0 1.1 2.2 3.3 4.4 5.5 6.6 7.7 8.8 9.9 10.10	Calculated using all bits of 6th byte of data
application	0.OPUS_APPLICATION_VOIP 1.OPUS_APPLICATION_AUDIO 2.OPUS_APPLICATION_RESTRICTED_LOWDELAY	Calculated using all bits of 7th byte of data
setDTX	0.0 1.1	Calculated using bit 0 of 8th byte of data
signal	0.OPUS_AUTO 1.OPUS_SIGNAL_VOICE 2.OPUS_SIGNAL_MUSIC	Calculated using bit 0 and bit 1 of 9th byte of data
setVBR	0.0 1.1	Calculated using bit 0 of 10th byte of data
setVBRConstraint	0.0 1.1	Calculated using bit 0 of 11th byte of data
forceChannel	0.OPUS_AUTO 1.1 2.2	Calculated using all bits of 12th byte of data
maxBandwidth	0.OPUS_BANDWIDTH_NARROWBAND 1.OPUS_BANDWIDTH_MEDIUMBAND 2.OPUS_BANDWIDTH_WIDEBAND 3.OPUS_BANDWIDTH_SUPERWIDEBAND 4.OPUS_BANDWIDTH_FULLBAND	Calculated using all bits of 13th byte of data
setInbandFec	0.0 1.1	Calculated using bit 0 of 14th byte of data
pktLoss	0.0 1.1 2.2 3.5	Calculated using all bits of 15th byte of data
lsbDepth	0.8 1.24	Calculated using bit 0 of 16th byte of data
setPredDisable	0.0 1.1	Calculated using bit 0 of 17th byte of data
frameSizeEnum	0.OPUS_FRAMESIZE_2_5_MS 1.OPUS_FRAMESIZE_5_MS 2.OPUS_FRAMESIZE_10_MS 3.OPUS_FRAMESIZE_20_MS 4.OPUS_FRAMESIZE_40_MS 5.OPUS_FRAMESIZE_60_MS 6.OPUS_FRAMESIZE_80_MS 7.OPUS_FRAMESIZE_100_MS 8.OPUS_FRAMESIZE_120_MS	Calculated using all bits of 18th byte of data

Maximize utilization of input data

The plugin feeds the entire input data to the codec. For buffer size which is not a multiple of mNumPcmBytesPerInputFrame, we will accumulate the input and keep it. Once the input is filled with expected number of bytes, we will send it to encoder. This ensures that the plugin tolerates any kind of input (empty, huge, malformed, etc) and doesnt exit() on any input and thereby increasing the chance of identifying vulnerabilities.

Build

This describes steps to build opus_enc_fuzzer and opus_multistream_enc_fuzzer.

Android

Steps to build

Build the fuzzer

  $ mm -j$(nproc) opus_enc_fuzzer
  $ mm -j$(nproc) opus_multistream_enc_fuzzer

Steps to run

Create a directory CORPUS_DIR and copy some raw media files to that folder. Push this directory to device.

To run on device

  $ adb sync data
  $ adb shell /data/fuzz/arm64/opus_enc_fuzzer/opus_enc_fuzzer CORPUS_DIR
  $ adb shell /data/fuzz/arm64/opus_multistream_enc_fuzzer/opus_multistream_enc_fuzzer CORPUS_DIR

To run on host

  $ $ANDROID_HOST_OUT/fuzz/x86_64/opus_enc_fuzzer/opus_enc_fuzzer CORPUS_DIR
  $ $ANDROID_HOST_OUT/fuzz/x86_64/opus_multistream_enc_fuzzer/opus_multistream_enc_fuzzer CORPUS_DIR

References:

• http://llvm.org/docs/LibFuzzer.html
• https://github.com/google/oss-fuzz