Data Rust active any

Initialize raw or vector storage before making elements visible

data-rust-033

Intent

Prevent undefined behavior from exposing uninitialized Rust storage as live elements.

Applicability

Applies to unsafe Rust manipulating raw storage or vector internals. Return unknown when unsafe details are hidden.

What to inspect

set_len, raw pointers, MaybeUninit, writes into capacity, and when elements become logically initialized.

Pass criteria

Unsafe code fully initializes memory before adjusting length or otherwise exposing elements to safe code.

Fail criteria

Code marks elements as initialized before writing them or reads or drops uninitialized storage.

Do not flag

Safe Rust collection APIs that already preserve initialization guarantees.

Confidence guidance

HIGH when set_len or raw pointers make uninitialized data visible. MEDIUM when helper invariants may exist off-screen. LOW when the unsafe block is incomplete in the diff.

Remediation

Use MaybeUninit patterns and only expose elements after successful initialization.

Pass example

ptr.write(value);
vec.set_len(len + 1);

Fail example

vec.set_len(len + 1);
ptr.write(value);