I bring up full validation because the concern here is putting in a speculative fix. If the ask is, why was the hardware like that in the first place the answer is because it can't be fully validated. If the ask is why should a speculative fix go into the Kernel it is because the consumers are not on top of tree and if a fix has a chance of never being exploited it needs to be pulled in years ahead so it goes into an LTR that customers migrate to BEFORE the issue comes up.

[–] firelizzard 7 points 4 weeks ago (1 children)

If the ask is, why was the hardware like that in the first place the answer is because it can’t be fully validated.

But that's not the question. There are two questions: Who should be responsible for patching hardware vulnerabilities? And if the answer is "the kernel" then should speculative but never demonstrated vulnerabilities be patched? Linus' answer is the hardware manufacturer, and no.

Is this really the hardware vendor’s problem though? It’s the consumers problem.

Maybe we're running into the ambiguity of language. If you mean to say, "Who does it cause a problem for? The consumer." then sure. On the other hand what I mean, and what I think Linus means, is "Who's responsible for the vulnerability existing? Hardware vendors. Who should fix it? Hardware vendors."

If the ask is why should a speculative fix go into the Kernel [...]

Depends on what you/we/they mean by "speculative". IMO, we need to do something (microcode, kernel patches, whatever) to patch Spectre and Meltdown. Those have been demonstrated to be real vulnerabilities, even if no one has exploited them yet. But "speculative" can mean something else. I'm not going to read all the LMK emails so maybe they're talking about something else. But I've seen plenty of, "Well if X, Y, and Z happen then that could be a vulnerability." For that kind of speculative vulnerability, one that has not been demonstrated to be a real vulnerability, I am sympathetic to Linus' position.

[–] [email protected] 2 points 4 weeks ago

This is a patch from the hardware vendor so I am assuming that the ask is not that the hardware vendor take responsibility but that they not release buggy hardware. That is what I mean about the validation issue.

The attack vector is shared in the patch so it isn't entirely a theory.

There is a comment from Linus about how this patch is only needed for some hardware and doesn't apply to others but I don't get his relevance there as different hardware validates against different use cases and their source logic might be entirely disparate.

So my validation talk is simply saying that bugs happen. My concern here is what more should a hardware vendor do beyond submitting a kernel patch? You can't just not have the bug, and if you recall the part someone else will just keep theirs in the field and take all the market share and roll the dice that their bugs don't get exploited.