rust-lang/futures-rs · Security
MutexGuard::map can cause a data race in safe code
- GHSA ID
- GHSA-rh4w-94hh-9943
- CVE ID
- CVE-2020-35905
- Severity
- medium
- Published
- Updated
- CVSS
- 4.7 · CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
- CVSS v3
- 4.7 · CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Description
Affected versions of the crate had a Send/Sync implementation for MappedMutexGuard that only considered variance on T, while MappedMutexGuard dereferenced to U.
This could of led to data races in safe Rust code when a closure used in MutexGuard::map() returns U that is unrelated to T.
The issue was fixed by fixing Send and Sync implementations, and by adding a PhantomData<&'a mut U> marker to the MappedMutexGuard type to tell the compiler that the guard is over U too.
CWEs
- CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')