The bug relies on undefined behaviour in the C language, but it’s exploitable is due to the way memory access operations are written in C. Equivalent Rust code would not be exploitable at a language level because that type of raw pointer array access isn’t possible with resorting to unsafe blocks. The undefined behaviour that caused the bug also doesn’t not exist in Rust.

Yes. If you index out of bounds in a Rust program, it will raise a panic. This is infinitely better than causing memory unsafety and creating a remote code execution exploit, and the best you can possibly do.

If the code were entirely analogous, that is correct, unless the Rust code used some kind of `unsafe` tricks in order to increase performance (this is fairly common in advanced Rust code).

That being said, whether a runtime panic leads to DoS depends on the execution model. In web applications, threads are usually mapped to connections in some way, and a runtime panic only unwinds the thread it occurs in, so this wouldn't necessarily mean that other users experience service disruptions.

More to the point, I'd expect modern application and/or library code to include default safety checks that prevent scenarios like absurdly large queries from happening in the first place, and provide recoverable errors if such pathological inputs are encountered.