It already exists! https://github.com/cuviper/alloc_geiger

Hahaha, perfect! Edit: Wow, I love that this does specifically that, too.

Not Rust, but it's very easy to wrap malloc under gcc for this kind of thing (or something more useful). Compile with --wrap=malloc and:

    void *__real_malloc(size_t);
    void *__wrap_malloc(size_t size) {
        ...
        return __real_malloc(size);
    }

Thank you for sharing this!