This is a small project for fuzzing Apache Commons Codec with the jazzer fuzzing tool.
See Fuzzing for a general description of the theory behind fuzzy testing.
Because Java uses a runtime environment which does not crash on invalid actions of an
application (unless native code is invoked), Fuzzing of Java-based applications
focuses on the following:
- verify if only expected exceptions are thrown
- verify any JNI or native code calls
- find cases of unbounded memory allocations
Apache Commons Codec does not use JNI or native code, therefore the fuzzing target mainly tries to trigger unexpected exceptions and unbounded memory allocations.
Build the fuzzing target:
./gradlew shadowJar
If possible, provide a corpus of test-documents in a folder corpus. This improves
fuzzing a lot, both valid encoded documents and slighlty broken ones help the
fuzzer to come up with interesting cases.
Download Jazzer from the releases page,
choose the latest version and select the file jazzer-<os>-<version>.tar.gz
Unpack the archive:
tar xzf jazzer-*.tar.gz
Create the corpus-directories
mkdir -p corpus corpusDigest corpusLanguage
Invoke the fuzzing:
./jazzer --cp=build/libs/codec-fuzz-all.jar --instrumentation_includes=org.apache.commons.** --target_class=org.dstadler.codec.fuzz.Fuzz -rss_limit_mb=4096 corpus
Invoke the fuzzing for "digest" package:
./jazzer --cp=build/libs/codec-fuzz-all.jar --instrumentation_includes=org.apache.commons.** --target_class=org.dstadler.codec.fuzz.FuzzDigest -rss_limit_mb=4096 corpusDigest
Invoke the fuzzing for "language" package:
./jazzer --cp=build/libs/codec-fuzz-all.jar --instrumentation_includes=org.apache.commons.** --target_class=org.dstadler.codec.fuzz.FuzzLanguage -rss_limit_mb=4096 corpusLanguage
In this mode Jazzer will stop whenever it detects an unexpected exception or crashes.
You can use --keep_going=10 to report a given number of exceptions before stopping.
See ./jazzer for options which can control details of how Jazzer operates.
Copyright 2021-2024 Dominik Stadler
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.