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:

• 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:

• time::at_utc
• time::at
• time::now
• time::tzset

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:

• chronotope/chrono#602 (comment)
• vityafx/serde-aux#21

If a close_notify alert is received during a handshake, complete_io does not terminate.

Callers which do not call complete_io are not affected.

rustls-tokio and rustls-ffi do not call complete_io and are not affected.

rustls::Stream and rustls::StreamOwned types use complete_io and are affected.

The following presentation at this year's DEF CON was brought to our attention on the Diesel Gitter Channel:

SQL Injection isn't Dead: Smuggling Queries at the Protocol Level
http://web.archive.org/web/20240812130923/https://media.defcon.org/DEF%20CON%2032/DEF%20CON%2032%20presentations/DEF%20CON%2032%20-%20Paul%20Gerste%20-%20SQL%20Injection%20Isn't%20Dead%20Smuggling%20Queries%20at%20the%20Protocol%20Level.pdf
(Archive link for posterity.) Essentially, encoding a value larger than 4GiB can cause the length prefix in the protocol to overflow, causing the server to interpret the rest of the string as binary protocol commands or other data.

It appears Diesel does perform truncating casts in a way that could be problematic, for example: https://github.com/diesel-rs/diesel/blob/ae82c4a5a133db65612b7436356f549bfecda1c7/diesel/src/pg/connection/stmt/mod.rs#L36

This code has existed essentially since the beginning, so it is reasonable to assume that all published versions <= 2.2.2 are affected.

Mitigation

The prefered migration to the outlined problem is to update to a Diesel version newer than 2.2.2, which includes fixes for the problem.

As always, you should make sure your application is validating untrustworthy user input. Reject any input over 4 GiB, or any input that could encode to a string longer than 4 GiB. Dynamically built queries are also potentially problematic if it pushes the message size over this 4 GiB bound.

For web application backends, consider adding some middleware that limits the size of request bodies by default.

Resolution

Diesel now uses #[deny] directives for the following Clippy lints:

• cast_possible_truncation
• cast_possible_wrap
• cast_sign_loss

to prevent casts that will lead to precision loss or other trunctations. Additionally we performed an audit of the relevant code.

A fix is included in the 2.2.3 release.

Diesel allows users to configure various options for PostgreSQL's COPY FROM and COPY TO statements. These configurations are partially provided as strings or characters.

Diesel did not check if any these user-provided options contain a quote character ', which can lead to the injection of additional options in the current COPY FROM/COPY TO statement.

This vulnerability affects any user of COPY FROM/COPY TO that passes user-provided input to any of the affected functions. It can result in modifications of options in the current statement, but it is not possible inject additional statements.

Mitigation

The preferred mitigation to the outlined problem is to update to Diesel version 2.3.8 or newer, which includes fixes for the problem.

Resolution

Diesel now correctly escapes any quotes contained in the provided arguments.

Diesel allows to register custom aggregate SQL functions for SQLite via the SqliteAggregate interface.

To store an instance of the custom aggregate processor Diesel relied on the sqlite3_aggregate_context function provided by sqlite. This function doesn't provide any guarantees about alignment of the returned allocation, which in turn can lead to problems if the type implementing requires a special alignment, e.g. via a custom #[align(x)] attribute on the type implementing this trait. This affects any user of SqliteAggregate that registers the custom aggregate function with an SQLite connection, while using a non-standard alignment on the type implementing this trait.

Mitigation

The preferred mitigation to the outlined problem is to update to a Diesel version 2.3.8 or newer, which includes fixes for the problem.

Resolution

Diesel now allocates the corresponding memory on Rust side to get a correctly aligned allocation.