RUSTSEC-2020-0071: Potential segfault in the time crate

[github-actions]

Potential segfault in the time crate

Details
Package	time
Version	0.1.43
URL	time-rs/time#293
Date	2020-11-18
Patched versions	>=0.2.23
Unaffected versions	=0.2.0,=0.2.1,=0.2.2,=0.2.3,=0.2.4,=0.2.5,=0.2.6

Impact

Unix-like operating systems may segfault due to dereferencing a dangling pointer in specific circumstances. This requires an environment variable to be set in a different thread than the affected functions. This may occur without the user's knowledge, notably in a third-party library.

The affected functions from time 0.2.7 through 0.2.22 are:

• time::UtcOffset::local_offset_at
• time::UtcOffset::try_local_offset_at
• time::UtcOffset::current_local_offset
• time::UtcOffset::try_current_local_offset
• time::OffsetDateTime::now_local
• time::OffsetDateTime::try_now_local

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

• at
• at_utc

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

No workarounds are known.

References

time-rs/time#293

See advisory page for additional details.

[syphar]

@jyn514 checking which crates use this old version, and there are more:

time v0.1.43
├── chrono v0.4.19
│   ├── chrono-tz v0.6.0
│   │   └── tera v1.13.0
│   │       └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   ├── postgres-types v0.2.2
│   │   ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   └── tokio-postgres v0.7.4
│   │       └── postgres v0.19.2
│   │           ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │           ├── r2d2_postgres v0.18.1
│   │           │   └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │           └── schemamama_postgres v0.3.0
│   │               └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   ├── rusoto_credential v0.46.0
│   │   ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   ├── rusoto_core v0.46.0
│   │   │   ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   │   └── rusoto_s3 v0.46.0
│   │   │       └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   └── rusoto_signature v0.46.0
│   │       └── rusoto_core v0.46.0 (*)
│   ├── sentry-core v0.23.0
│   │   ├── sentry v0.23.0
│   │   │   └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   ├── sentry-anyhow v0.23.0
│   │   │   └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   ├── sentry-backtrace v0.23.0
│   │   │   ├── sentry v0.23.0 (*)
│   │   │   ├── sentry-anyhow v0.23.0 (*)
│   │   │   └── sentry-panic v0.23.0
│   │   │       ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   │       └── sentry v0.23.0 (*)
│   │   ├── sentry-contexts v0.23.0
│   │   │   └── sentry v0.23.0 (*)
│   │   ├── sentry-log v0.23.0
│   │   │   └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   │   └── sentry-panic v0.23.0 (*)
│   ├── sentry-types v0.23.0
│   │   └── sentry-core v0.23.0 (*)
│   ├── systemstat v0.1.10
│   │   └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│   └── tera v1.13.0 (*)
├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
├── hyper v0.10.16
│   └── iron v0.6.1
│       ├── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
│       └── router v0.6.0
│           └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
└── zip v0.5.13
    └── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)
[build-dependencies]
└── docs-rs v0.6.0 (/Users/syphar/src/rust-lang/docs.rs)

• there is a PR for zip, Upgrade time dependency to "0.3" zip-rs/zip-old#254
• also for chrono, Bump time to 0.3 chronotope/chrono#578
• hyper doesn't depend on time any more in recent releases, but iron uses the old version
  while we could fix our own usages, iron will block us fixing this.

I'm not a security specialist, but it seems like a possible attacker exposing this would need access to our server, or the build pipeline, so I believe we're fine with ignoring this error.

[jyn514]

Yeah, as long as no one is using set_var we should be fine.

[jhpratt]

Yeah, as long as no one is using set_var we should be fine.

As the maintainer of the time crate I'm confirming this is correct. That said, it can't be called anywhere in the dependency tree. Every single dep would need to be checked on every single version bump to be 100% certain.

[jyn514]

@jhpratt realistically we don't have a choice here, switching away from iron is a multi-month project.

[jhpratt]

For sure. I'm just saying it's not easy because it transgresses crates.