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crossbeam-utils Unsoundness of AtomicCell<{i,u}64> arithmetics on 32-bit targets that support Atomic{I,U}64

High severity GitHub Reviewed Published Feb 14, 2022 in crossbeam-rs/crossbeam • Updated Feb 4, 2025

Package

cargo crossbeam-utils (Rust)

Affected versions

< 0.8.7

Patched versions

0.8.7

Description

Impact

The affected versions of this crate incorrectly assumed that the alignment of {i,u}64 was always the same as Atomic{I,U}64.

However, the alignment of {i,u}64 on a 32-bit target can be smaller than Atomic{I,U}64.

This can cause the following problems:

  • Unaligned memory accesses
  • Data race

Crates using fetch_* methods with AtomicCell<{i,u}64> are affected by this issue.

32-bit targets without Atomic{I,U}64 and 64-bit targets are not affected by this issue.
32-bit targets with Atomic{I,U}64 and {i,u}64 have the same alignment are also not affected by this issue.

The following is a complete list of the builtin targets that may be affected. (last update: nightly-2022-02-11)

  • armv7-apple-ios (tier 3)
  • armv7s-apple-ios (tier 3)
  • i386-apple-ios (tier 3)
  • i586-unknown-linux-gnu
  • i586-unknown-linux-musl
  • i686-apple-darwin (tier 3)
  • i686-linux-android
  • i686-unknown-freebsd
  • i686-unknown-haiku (tier 3)
  • i686-unknown-linux-gnu
  • i686-unknown-linux-musl
  • i686-unknown-netbsd (tier 3)
  • i686-unknown-openbsd (tier 3)
  • i686-wrs-vxworks (tier 3)

(script to get list)

Patches

This has been fixed in crossbeam-utils 0.8.7.

Affected 0.8.x releases have been yanked.

References

crossbeam-rs/crossbeam#781

License

This advisory is in the public domain.

References

@taiki-e taiki-e published to crossbeam-rs/crossbeam Feb 14, 2022
Published by the National Vulnerability Database Feb 15, 2022
Published to the GitHub Advisory Database Feb 16, 2022
Reviewed Feb 16, 2022
Last updated Feb 4, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(66th percentile)

Weaknesses

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently. Learn more on MITRE.

CVE ID

CVE-2022-23639

GHSA ID

GHSA-qc84-gqf4-9926

Source code

Credits

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