alt Hacker NewsI am far from a security expert, but from the number of "we missed a single line C check across files during refactoring" critical security bugs discovered on a regular basis these days, the whole premise of a "giant secure open source C codebase" seems questionable. It is not specific to C of course, but invariants are arguably even harder to enforce and track consistently (esp under changes to code) in C. Unsure if FP with invariants encoded in types is a practically feasible scalable solution either. Model checking? [LLM] fuzzing? Fewer primitives with clear boundaries? Is that how seLinux was "checked"?
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The premise of a secure open codebase is fine.
The problem is being more auditable does not automatically make it more audited.
There have to be enough people with skill taking enough time to work on it.
To translate to Rust, it would have been "we missed a single line Rust check"...
This is a bug involving intersecting concerns and a deficit of cross-domain knowledge. It probably would have been the same in Lisp or assembly language.
The lesson here is that if a feature (at a minimum) does not have a associated test case, it is not actually a feature.
The whole premise of a "giant secure open source C codebase" seems questionable
Because code review is sometimes not much different from an idealized version of the halting problem, where you would have access to a formalized version of a specification.
In other words, there is no strict definition of what is a security issue.
In open source, someone (many, many) someone’s can at least check.
Closed source…..
While I can see the shortcomings of C and generally don't recommend it for new projects I don't see this particular bug as a good example of something Rust's borrow checker or some other language's type system will catch. I don't think even static analyzers can catch this.
It's basically something like this:
original: DoTheThing()
new: DoTheThingSlightlyDifferentButKeepMyCredentialsAlive()
fix: DoTheThingSlightlyDifferentButDoInFactNOTKeepMyCredentialsAlive()
In my experience a substantial portion of gnarly bugs come down to a violation of a high-level system invariant and those do not strike me as something that can be automated. Even with something like Lean you can prove your program satisfies certain properties but you need to have thought about those properties in the first place. The proof doesn't discover the invariant for you.
If you'd had thought about the relevant security property you could have written a regression test for it which is not hard. IMO the really hard part isn't expressing the implementation safely, but it's the realization that this was a property the implementation needed to preserve.