HistoryEdit

RUSTSEC-2020-0059

MutexGuard::map can cause a data race in safe code

Issued
Package
futures-util (crates.io)
Type
Vulnerability
Categories
Keywords
#concurrency #memory-corruption #memory-management
Aliases
Details
https://github.com/rust-lang/futures-rs/issues/2239
CVSS Score
4.7 MEDIUM
CVSS Details
Attack vector
Local
Attack complexity
High
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS Vector
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Patched
  • >=0.3.7
Unaffected
  • <0.3.2
Keywords
#concurrency #memory-corruption #memory-management
Affected Functions
Version
futures_util::lock::MutexGuard::map
  • >=0.3.2

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.