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.

[clintfred]

Looks like we may want to look into replacing chrono with time 0.3 according to: chronotope/chrono#602

chrono is going to open a CVE as well since it is doing something similar to time (in addition to actually depending on time). I suspect this will start a mass transition away from chrono.

It will take a little digging to figure out if we can replace chrono easily. If we want to do this it will require a major version bump since we use the chrono::DateTime type in our public API.

[clintfred]

We don't directly depend on time and our usages of chrono aren't doing anything with localtime, so we probably aren't affected. I still think replacing our usages of chrono is worth consideration. We'll see if chrono fixes their issue in a timely manner or not, I guess.