Link: https://zig.guide/standard-library/allocators/
Text:
> The Zig standard library also has a general-purpose debug allocator. This is a safe allocator that can prevent double-free, use-after-free and can detect leaks.
For more detail, see:
https://github.com/ziglang/zig/issues/3180#issuecomment-5284...
Here's the code: https://codeberg.org/ziglang/zig/src/commit/e44e927d33d37c44...
The closest callout in the doc comment is:
>Never reuses memory addresses, making it easier for Zig to detect branch on undefined values in case of dangling pointers. This relies on the backing allocator to also not reuse addresses.
But it's not really clear what this means. "branch on undefined values" would I think indicate that maybe they're doing a fill pattern that the compiler can detect at runtime when dereferenced? But I don't see it in the `free` path. It's not clear if this is deterministic or not either.
Or, rather, you can use a value after freeing it, but it will not be exploitable, because it will contain valid data of the right type. This is the same idea as Type-After-Type,
https://dl.acm.org/doi/10.1145/3274694.3274705
(Also similar to when you use indexes to an array in Rust and happen to read from a wrong but in-bounds index.)