Comment by ralfj
1 year ago
> It reads 42h because that address is hardcoded,
It is trivial to change this example into an arbitrary int2ptr cast.
> Go (or Python, or any of the other mainstream languages that do shared-memory concurrency and don't have Rust's type system),
As the article discusses, only Go has this issue. Python and Java and JavaScript and so on are all memory-safe. Maybe you are mixing up "language has data races" and "data races can cause the language itself to be broken"?
> If people want to make PLT arguments about Rust's correctness advantages, I will step out of the way and let them do that. But this article makes a security claim, and that claim is in the practical sense false.
This article makes a claim about the term "memory safety". You are making the claim that that's a security term. I admit I am not familiar with the full history of the term "memory safety", but I do know that "type safety" has been used in PLT for many decades, so it's not like all "safety" terms are somehow in the security domain.
I am curious what your definition of "memory safety" is such that Go satisfies the definition. Wikipedia defines it as
> Memory safety is the state of being protected from various software bugs and security vulnerabilities when dealing with memory access, such as buffer overflows and dangling pointers.
My example shows that Go does not enforce memory safety according to that definition -- and not through some sort of oversight or accident, but by design. Out-of-bounds reads and writes are possible in Go. The example might be contrived, but the entire point of memory safety guarantees is that it doesn't matter how contrived the code is.
I'm completely fine with Go making that choice, but I am not fine with Go then claiming to be memory safe in the same sense that Java or Rust are, when it is demonstrably not the case.
The problem isn't that you couldn't hardcode a scarier value; it's that you have to demonstrate a plausible scenario in realistic code where an attacker controls both the value and the address it's written to.
While you're wondering why I keep claiming Go is a memory-safe language, you can also go ask the ISRG, which says the same thing I am at (checks notes) https://www.memorysafety.org/.
> While you're wondering why I keep claiming Go is a memory-safe language, you can also go ask the ISRG, which says the same thing I am at
And yet Go violates the definition they give -- it doesn't prevent out-of-bounds accesses. (And just to be sure we're talking about the same thing, I'm specifically talking about Go here. All the other languages on their list are actually memory safe, as far as I know.)
> you have to demonstrate a plausible scenario in realistic code where an attacker controls both the value and the address it's written to.
So your definition of memory safety includes some notion of "plausible" and "realistic"? Neither https://www.memorysafety.org/docs/memory-safety/ nor Wikipedia have such a qualification in their definition. It would help if you could just spell out your definition in full, rather than having us guess.
> So your definition of memory safety includes some notion of "plausible" and "realistic"? Neither https://www.memorysafety.org/docs/memory-safety/ nor Wikipedia have such a qualification in their definition. It would help if you could just spell out your definition in full, rather than having us guess.
This is a strawman argument, you're arguing semantics here. You're a smart person, so you know exactly what he means. The perception created by your article is that people shouldn't use Go because it's not memory-safe. But the average developer hearing "not memory-safe" thinks of C/C++ level issues, with RCEs everywhere.
Unless you can show a realistic way this could be exploited for RCE in actual programs, you're just making noise. Further down the thread, you admit yourself that you're in a PLT research bubble and it shows.
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You're just wrong about this. The ability to write contrived code that does an out-of-bounds write, or to induce crashes, doesn't violate the notion of "memory safety" as an ordinary term of art.
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