rust-lang / rust-lang/rust-bindgen

`_bindgen_union_align` field in generated Rust union results in garbage data on AArch64 (e.g. Apple Silicon)

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bug I-ABI-bug
Dominant language
Rust
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Avg merge
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Merged PRs (30d)
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Description

See https://users.rust-lang.org/t/on-apple-silicon-bindgen-union-is-constructed-with-random-data/54469/ for a write-up and context. This may or may not be a security issue, since it's reading arbitrary memory.

Contributor guide

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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

Start with the linked Rust forum write-up and investigate the generated Rust union field named _bindgen_union_align on AArch64, such as Apple Silicon. Reproduce the garbage-data behavior and trace it through bindgen's generated bindings; done means the union no longer contains arbitrary data on the affected target.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
tooling
Issue type
Bug
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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