Stream: git-wasmtime

Topic: wasmtime / PR #14713 environ: align VMContext function re...

Wasmtime GitHub notifications bot (Oct 14 2026 at 01:50):

qiyuhuating opened PR #14713 from qiyuhuating:fix/vmctx-odd-tag-function-ref-alignment to bytecodealliance:main:

Summary

Fixes #14671.

Defined tags use four-byte slots; an odd count can misalign the following pointer-sized func_refs and subsequent fields on 64-bit targets. Add align { ptr } between tags and func_refs in the shared VMContext layout.

Changes

• Correct pointer alignment without unnecessary padding on 32-bit targets.
• Add offset regression tests for 32/64-bit pointers and 0–3 defined tags.
• Assert alignment of func_refs, startup_func_ref, and runtime_data_bases.

Verification

Source diff reviewed. Rust compilation, formatting, and tests are not yet run. Recommended: cargo test -p wasmtime-environ vmctx_function_references_are_aligned_after_tags and cargo fmt --all -- --check.

Wasmtime GitHub notifications bot (Oct 14 2026 at 01:50):

qiyuhuating requested dicej for a review on PR #14713.

Wasmtime GitHub notifications bot (Oct 14 2026 at 01:50):

qiyuhuating requested wasmtime-core-reviewers for a review on PR #14713.

Wasmtime GitHub notifications bot (Oct 14 2026 at 14:41):

:cross_mark: alexcrichton closed without merge PR #14713.

Wasmtime GitHub notifications bot (Oct 14 2026 at 14:41):

alexcrichton commented on PR #14713:

Thanks for the PR but this is a source of UB and thus a security issue for Wasmtime. We'll be publishing an advisory at https://github.com/bytecodealliance/wasmtime/security/advisories/GHSA-p79w-pv2r-29qp and we've got PRs prepped to go into main today for this.

Wasmtime GitHub notifications bot (Oct 15 2026 at 06:24):

qiyuhuating commented on PR #14713:

Thanks for clarifying, @alexcrichton, and for handling the fix and advisory. I should have raised this through the security reporting process first. I'll leave the coordinated fix to you.

Last updated: Oct 31 2026 at 23:03 UTC