Object parsing fuzzer #4845
Merged
Object parsing fuzzer #4845
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
The standalone driver for libgit2's fuzzing targets makes use of functions from libgit2 itself. While this is totally fine to do, we need to make sure to always have libgit2 initialized via `git_libgit2_init` before we call out to any of these. While this happens in most cases as we call `LLVMFuzzerInitialize`, which is provided by our fuzzers and which right now always calls `git_libgit2_init`, one exception to this rule is our error path when not enough arguments have been given. In this case, we will call `git_vector_free_deep` without libgit2 having been initialized. As we did not set up our allocation functions in that case, this will lead to a segmentation fault. Fix the issue by always initializing and shutting down libgit2 in the standalone driver. Note that we cannot let this replace the initialization in `LLVMFuzzerInitialize`, as it is required when using the "real" fuzzers by LLVM without our standalone driver. It's no problem to call the initialization and deinitialization functions multiple times, though.
When failing to parse a raw object fromits data, we free the partially parsed object but then fail to propagate the error to the caller. This may lead callers to operate on objects with invalid memory, which will sooner or later cause the program to segfault. Fix the issue by passing up the error code returned by `parse_raw`.
Add a simple fuzzer that exercises our object parser code. The fuzzer is quite trivial in that it simply passes the input data directly to `git_object__from_raw` for each of the four object types.
|
/rebuild |
|
Okay, @pks-t, I started to rebuild this pull request. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This includes a new trivial object parsing fuzzer as well as fixes to both our standalone fuzzing driver as well as an error in the system under test.