25.11 Tools for Verifying Unsafe Code

Even with rigorous code reviews, unsafe code can harbor subtle memory errors. One effective tool for detecting such issues is Miri—an interpreter that can detect undefined behavior in Rust code, including:

  • Out-of-bounds memory access
  • Use-after-free errors
  • Invalid deallocations
  • Data races in single-threaded contexts (such as dereferencing freed memory)

Another widely known tool for spotting memory errors is Valgrind, which can also be used with Rust binaries.

25.11.1 Installing and Using Miri

Depending on your operating system, Miri may already be available alongside other Rust tools; if not, it can be installed via Rustup:

  1. Install Miri (if required):

    rustup component add miri

  2. Run Miri on your tests:

    cargo miri test

Miri interprets your code and flags invalid memory operations, helping verify that your unsafe code is correct. It can even detect memory leaks in safe Rust caused by cyclic data structures.