Re: [PATCH v5 02/12] array_idx: sanitize speculative array de-references

From: Linus Torvalds
Date: Tue Jan 30 2018 - 14:38:53 EST


On Mon, Jan 29, 2018 at 10:29 PM, Dan Williams <dan.j.williams@xxxxxxxxx> wrote:
>
> Of course, and everything about the technical feedback and suggestions
> was completely valid, on point, and made the patches that much better.
> What wasn't appreciated and what I am tired of grinning and bearing is
> the idea that it's only the maintainer that can show emotion, that
> it's only the maintainer that can be exasperated and burnt out.

Yeah, I think everybody is a bit tired of - and burnt out by - these
patches, and they are subtler and somewhat more core than most are,
which makes the stakes a bit higher too, and the explanations can be a
bit more difficult.

I think everybody is entitled to being a bit snippy occasionally.
Definitely not just maintainers.

So by all means, push right back.

Anyway, I do think the patches I've seen so far are ok, and the real
reason I'm writing this email is actually more about future patches:
do we have a good handle on where these array index sanitations will
be needed?

Also, while array limit checking was obviously the official
"spectre-v1" issue, I do wonder if there are possible other issues
where mispredicted conditional branches can end up leaking
information?

IOW, is there some work on tooling/analysis/similar? Not asking for
near-term, but more of a "big picture" question..

Linus