The fuzzer plugin for libmediatranscoder is designed based on the understanding of the transcoder and tries to achieve the following:
The configuration parameters are not hardcoded, but instead selected based on incoming data. This ensures more code paths are reached by the fuzzer.
Transcoder supports the following parameters:
dstMime
)profile
)profile
)level
)level
)bitrate
)Parameter | Valid Values | Configured Value |
---|---|---|
dstMime | 0. AMEDIA_MIMETYPE_VIDEO_AVC 1. AMEDIA_MIMETYPE_VIDEO_HEVC | Bit 0 (LSB) of 1st byte of data |
profile for AVC | 0. PROFILE_AVC_BASELINE 1. PROFILE_AVC_CONSTRAINED_BASELINE 2. PROFILE_AVC_MAIN | All bits of 2nd byte of data modulus 3 |
profile for HEVC | 0. PROFILE_HEVC_MAIN 1. PROFILE_HEVC_MAIN_STILL | All bits of 2nd byte of data modulus 2 |
level for AVC | 0. LEVEL_AVC_1 1. LEVEL_AVC_1B 2. LEVEL_AVC_1_1 3. LEVEL_AVC_1_2 4. LEVEL_AVC_1_3 5. LEVEL_AVC_2 6. LEVEL_AVC_2_1 7. LEVEL_AVC_2_2 8. LEVEL_AVC_3 9. LEVEL_AVC_3_1 10. LEVEL_AVC_3_2 11. LEVEL_AVC_4 12. LEVEL_AVC_4_1 13. LEVEL_AVC_4_2 14. LEVEL_AVC_5 | All bits of 3rd byte of data modulus 15 |
level for HEVC | 0. LEVEL_HEVC_MAIN_1 1. LEVEL_HEVC_MAIN_2 2. LEVEL_HEVC_MAIN_2_1 3. LEVEL_HEVC_MAIN_3 4. LEVEL_HEVC_MAIN_3_1 5. LEVEL_HEVC_MAIN_4 6. LEVEL_HEVC_MAIN_4_1 7. LEVEL_HEVC_MAIN_5 8. LEVEL_HEVC_MAIN_5_1 9. LEVEL_HEVC_MAIN_5_2 | All bits of 3rd byte of data modulus 10 |
bitrate | In the range 0 to 500000000 | All bits of 4th and 5th byte of data |
This also ensures that the plugin is always deterministic for any given input.
The plugin feeds the entire input data to the transcoder. 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.
This describes steps to build media_transcoder_fuzzer binary.
Build the fuzzer
$ mm -j$(nproc) media_transcoder_fuzzer
Create a directory CORPUS_DIR
$ adb shell mkdir CORPUS_DIR
To run on device
$ adb sync data $ adb shell /data/fuzz/${TARGET_ARCH}/media_transcoder_fuzzer/media_transcoder_fuzzer CORPUS_DIR