rust-lang / rust-lang/git2-rs

Diff::merge() causes double free

Open
#964 2 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

upstream
Dominant language
Rust
Stars
2.1k
Forks
450
Avg merge
11m
Merged PRs (30d)
1

Description

The library fails with a double free when merging two Diff's built from buffers. Is this intended to be supported?

Cargo.toml

[dependencies.git2]
version = "0.17.2"
default-features = false
features = ["vendored-libgit2"]
        use git2;

        let diff_a: &str = r#"
diff --git a/README.md b/README.md
index 18fb8328..ce60f40c 100644
--- a/README.md
+++ b/README.md
@@ -4,1 +4,2 @@ componentwise
 reusing
+proverb
"#
        .trim_start();
        let mut diff_a = git2::Diff::from_buffer(diff_a.as_bytes()).unwrap();

        let diff_b: &str = r#"
diff --git a/README.md b/README.md
index 18fb8328..ce60f40c 100644
--- a/README.md
+++ b/README.md
@@ -4,2 +4,3 @@ componentwise
 reusing
 proverb
+offended
"#
        .trim_start();
        let diff_b = git2::Diff::from_buffer(diff_b.as_bytes()).unwrap();

        diff_a.merge(&diff_b).expect("merge diff from buffers");

Results in:

free(): double free detected in tcache 2
error: test failed, to rerun pass `-p radicle-cli --lib`

Edit: simplified example and added Cargo information

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the failure with the Rust example using git2::Diff::from_buffer and Diff::merge, then inspect those entry points and their ownership behavior. Done means merging two buffer-created diffs no longer triggers a double free, with a regression test covering the example.

Written by the indexing model from the issue text.

Assessment

Tech stack
git, rust
Domain
devtools
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.