Add corpus support to local DotnetFuzzing runs and fuzz Deflate64 #121019
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Pull Request Overview
This PR adds corpus support to the DotnetFuzzing project for local runs, allowing fuzzers to use seed corpora instead of relying on dictionaries. The change improves fuzzing efficiency by providing proper initial test cases. The ZipArchiveFuzzer is updated to use a corpus, and a new Deflate64Fuzzer is introduced to test the managed Deflate64 decompression implementation.
- Adds corpus infrastructure to the fuzzing framework with validation and deployment logic
- Converts ZipArchiveFuzzer to use corpus instead of dictionary for better fuzzing effectiveness
- Introduces Deflate64Fuzzer to test internal Deflate64 decompression used in ZipArchive reading
Reviewed Changes
Copilot reviewed 6 out of 13 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| src/libraries/Fuzzing/DotnetFuzzing/Program.cs | Adds corpus directory handling, validation, and deployment logic for both OneFuzz and local runs |
| src/libraries/Fuzzing/DotnetFuzzing/IFuzzer.cs | Extends IFuzzer interface with optional Corpus property |
| src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/ZipArchiveFuzzer.cs | Adds corpus property to use seed files instead of dictionary |
| src/libraries/Fuzzing/DotnetFuzzing/Fuzzers/Deflate64Fuzzer.cs | New fuzzer for testing Deflate64 decompression with reflection-based stream creation |
| src/libraries/Fuzzing/DotnetFuzzing/DotnetFuzzing.csproj | Simplifies fuzzer file inclusion using wildcard and adds corpus files to build output |
| eng/pipelines/libraries/fuzzing/deploy-to-onefuzz.yml | Adds OneFuzz deployment task for new Deflate64Fuzzer |
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MihaZupan
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Oct 23, 2025
This was referenced Nov 5, 2025
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This PR introduces corpus support for the DotnetFuzzing project. Currently this works for local runs only (OneFuzz requires creating a special container for corpus, which probably needs to be done manually -- once per fuzzer, this is left for future work).
Currently, some fuzzers (IMO incorrectly) use dictionaries as a replacement for lack of corpus support, which makes fuzzing inefficient. This PR prepares ground for future improvements in this regard.
To validate the concept, this PR converts ZipArchive fuzzing to use corpus instead of a dictionary, and adds code to fuzz Deflate64 (for which we have managed implementation internal to reading ZipArchives).