v811_spc009/frameworks/av/drm/libmediadrm/fuzzer

Fuzzer for libmediadrm

Plugin Design Considerations

The fuzzer plugin for libmediadrm 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.

libmediadrm supports the following parameters:

1. Security Level (parameter name: securityLevel)
2. Mime Type (parameter name: mimeType)
3. Key Type (parameter name: keyType)
4. Crypto Mode (parameter name: cryptoMode)

Parameter	Valid Values	Configured Value
securityLevel	0.DrmPlugin::kSecurityLevelUnknown 1.DrmPlugin::kSecurityLevelMax 2.DrmPlugin::kSecurityLevelSwSecureCrypto 3.DrmPlugin::kSecurityLevelSwSecureDecode 4.DrmPlugin::kSecurityLevelHwSecureCrypto 5.DrmPlugin::kSecurityLevelHwSecureDecode 6.DrmPlugin::kSecurityLevelHwSecureAll	Value obtained from FuzzedDataProvider in the range 0 to 6
mimeType	0.video/mp4 1.video/mpeg 2.video/x-flv 3.video/mj2 4.video/3gp2 5.video/3gpp 6.video/3gpp2 7.audio/mp4 8.audio/mpeg 9.audio/aac 10.audio/3gp2 11.audio/3gpp 12.audio/3gpp2 13.video/unknown	Value obtained from FuzzedDataProvider in the range 0 to 13
keyType	0.DrmPlugin::kKeyType_Offline 1.DrmPlugin::kKeyType_Streaming 2.DrmPlugin::kKeyType_Release	Value obtained from FuzzedDataProvider in the range 0 to 2
cryptoMode	0.CryptoPlugin::kMode_Unencrypted 1.CryptoPlugin::kMode_AES_CTR 2.CryptoPlugin::kMode_AES_WV 3.CryptoPlugin::kMode_AES_CBC	Value obtained from FuzzedDataProvider in the range 0 to 3

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

Maximize utilization of input data

The plugin feeds the entire input data to the drm module. 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 mediadrm_fuzzer binary.

Android

Steps to build

Build the fuzzer

  $ mm -j$(nproc) mediadrm_fuzzer

Steps to run

Create a directory CORPUS_DIR

  $ adb shell mkdir CORPUS_DIR

To run on device

  $ adb sync data
  $ adb shell /data/fuzz/${TARGET_ARCH}/mediadrm_fuzzer/mediadrm_fuzzer CORPUS_DIR

References:

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