> Well, assume that we are eg looking at the 'sudo' program. In any case, almost any code can become harmful, if memory gets corrupted, and if attackers control the input.
Not really; OOB stores, sure, but, other than that, even something basic like username comparison or something resulting in OOB loads on too-long names could technically be completely safe if OOB loads were defined as "either returns an arbitrary value, or crashes", just resulting in superfluous rejections.
And, in a safe language, no matter how wrongly you'd implement flag/argument parsing (besides some equivalent of just straight up passing the args to system() or equivalent), as long as the final thing actually processing the request & comparing passwords doesn't assume anything specific of the parsed internal data format, it could cause no actual exploitable issues.
Assume that `do_something();` does some IO, and C is perfectly happy with that loop.
You could have also added extra conditions to make the loop look less infinite to the C compiler. Eg do a check in the loop body, and optionally break from it.
> Of course you still generally need to have whatever harmful code you don't want ran here to still be present in the binary somewhere, [...]
Well, assume that we are eg looking at the 'sudo' program. In any case, almost any code can become harmful, if memory gets corrupted, and if attackers control the input.