{"id":"GHSA-8f24-6m29-wm2r","summary":"use-after-free in tracing ","details":"The implementation of the [`Instrumented::into_inner`] method in affected versions of this crate contains undefined behavior due to incorrect use of [`std::mem::forget`] The function creates `*const` pointers to `self`, calls [`mem::forget(self)`][`std::mem::forget`], and then moves values out of those pointers using [`std::ptr::read`].\n\n```rust\n// To manually destructure `Instrumented` without `Drop`, we\n// move it into a ManuallyDrop and use pointers to its fields\nlet span: *const Span = &this.span;\nlet inner: *const ManuallyDrop\u003cT\u003e = &this.inner;\nmem::forget(self);\n// SAFETY: Those pointers are valid for reads, because `Drop` didn't\n//         run, and properly aligned, because `Instrumented` isn't\n//         `#[repr(packed)]`.\nlet _span = unsafe { span.read() };\nlet inner = unsafe { inner.read() };\n```\n\nHowever, the [`mem::forget` documentation][`std::mem::forget`] states:\n\n\u003e Any resources the value manages, such as heap memory or a file handle, will\n\u003e linger forever in an unreachable state. **However, it does not guarantee that\n\u003e pointers to this memory will remain valid.**\n\nThis means that these pointers are no longer valid. This could result in a stack use-after-free if LLVM chooses to reuse `self`'s stack slot for a rebinding after the call to [`std::mem::forget`].\n\nThis undefined behavior has not been observed to cause miscompilation as of Rust 1.73.0. However, any use of this method with the affected versions of `tracing` are unsound.\n\nThe flaw was corrected in commit [20a1762] ([PR #2765]) by replacing the use of [`std::mem::forget`] with `std::mem::ManuallyDrop`, ensuring that the stack slot is not reused and the pointers remain valid when they are read. The fix is\npublished in `tracing` [v0.1.40]. Affected versions have been yanked from crates.io.\n\nThanks to [Taylor Cramer] and [Manish Goregaokar] for finding and correcting\nthis issue!\n\n[`Instrumented::into_inner`]:\n    https://docs.rs/tracing/latest/tracing/instrument/struct.Instrumented.html#method.into_inner\n[`std::mem::forget`]: https://doc.rust-lang.org/std/mem/fn.forget.html\n[`std::ptr::read`]:\n    https://doc.rust-lang.org/std/primitive.pointer.html#method.read-1\n[20a1762]:\n    https://github.com/tokio-rs/tracing/commit/20a1762b3fd5f1fafead198fd18e469c68683721\n[PR #2765]: https://github.com/tokio-rs/tracing/pull/2765\n[v0.1.40]: https://crates.io/crates/tracing/0.1.40\n[Taylor Cramer]: https://github.com/cramertj\n[Manish Goregaokar]: https://github.com/manishearth\n","aliases":["RUSTSEC-2023-0078"],"modified":"2024-02-10T16:26:48.362242Z","published":"2024-01-17T20:32:35Z","database_specific":{"github_reviewed":true,"github_reviewed_at":"2024-01-17T20:32:35Z","nvd_published_at":null,"cwe_ids":["CWE-416"],"severity":"MODERATE"},"references":[{"type":"WEB","url":"https://github.com/tokio-rs/tracing/pull/2765"},{"type":"WEB","url":"https://github.com/tokio-rs/tracing/commit/20a1762b3fd5f1fafead198fd18e469c68683721"},{"type":"PACKAGE","url":"https://github.com/tokio-rs/tracing"},{"type":"WEB","url":"https://github.com/tokio-rs/tracing/releases/tag/tracing-0.1.40"},{"type":"WEB","url":"https://rustsec.org/advisories/RUSTSEC-2023-0078.html"}],"affected":[{"package":{"name":"tracing","ecosystem":"crates.io","purl":"pkg:cargo/tracing"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0.1.38"},{"fixed":"0.1.40"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2024/01/GHSA-8f24-6m29-wm2r/GHSA-8f24-6m29-wm2r.json"}}],"schema_version":"1.9.0"}