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RUSTSEC-2020-0071

Potential segfault in the time crate
Reported
Issued
Package
time (crates.io)
Type
Vulnerability
Categories
Keywords
#segfault
Aliases
References
CVSS Score
6.2 MEDIUM
CVSS Details
Attack vector
Local
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
CVSS Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Patched
  • >=0.2.23
Unaffected
  • =0.2.0
  • =0.2.1
  • =0.2.2
  • =0.2.3
  • =0.2.4
  • =0.2.5
  • =0.2.6
Affected OSes
  • linux
  • redox
  • solaris
  • android
  • ios
  • macos
  • netbsd
  • openbsd
  • freebsd
Affected Functions
Version
time::OffsetDateTime::now_local
  • <0.2.23
time::OffsetDateTime::try_now_local
  • <0.2.23
time::UtcOffset::current_local_offset
  • <0.2.23
time::UtcOffset::local_offset_at
  • <0.2.23
time::UtcOffset::try_current_local_offset
  • <0.2.23
time::UtcOffset::try_local_offset_at
  • <0.2.23
time::at
  • ^0.1
time::at_utc
  • ^0.1
time::now
  • ^0.1

Description

Impact

The affected functions set environment variables without synchronization. On Unix-like operating systems, this can crash in multithreaded programs. Programs may segfault due to dereferencing a dangling pointer if an environment variable is read in a different thread than the affected functions. This may occur without the user's knowledge, notably in the Rust standard library or third-party libraries.

The affected functions from time 0.2.7 through 0.2.22 are:

The affected functions in time 0.1 (all versions) are:

Non-Unix targets (including Windows and wasm) are unaffected.

Patches

Pending a proper fix, the internal method that determines the local offset has been modified to always return None on the affected operating systems. This has the effect of returning an Err on the try_* methods and UTC on the non-try_* methods.

Users and library authors with time in their dependency tree should perform cargo update, which will pull in the updated, unaffected code.

Users of time 0.1 do not have a patch and should upgrade to an unaffected version: time 0.2.23 or greater or the 0.3 series.

Workarounds

A possible workaround for crates affected through the transitive dependency in chrono, is to avoid using the default oldtime feature dependency of the chrono crate by disabling its default-features and manually specifying the required features instead.

Examples:

Cargo.toml:

chrono = { version = "0.4", default-features = false, features = ["serde"] }

chrono = { version = "0.4.22", default-features = false, features = ["clock"] }

Commandline:

cargo add chrono --no-default-features -F clock

Sources:

Advisory available under CC0-1.0 license.