Re: [lkp-robot] [include/linux/string.h] 6974f0c455: kernel_BUG_at_lib/string.c

From: Kees Cook
Date: Tue Jul 25 2017 - 20:38:18 EST

On Tue, Jul 25, 2017 at 5:11 PM, Linus Torvalds
<torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Tue, Jul 25, 2017 at 4:35 PM, Kees Cook <keescook@xxxxxxxxxxxx> wrote:
>> In this case, there isn't a sensible way to continue.
> Kees, stop this idiocy already.
> These have been FALSE POSITIVES. They haven't actually been bugs in
> the code, they have been bugs in the *checking* code.
> In two years, when this code is actually trusted, that would be one thing.

Okay, fair enough. As long as there is a time horizon where this can
operate as an actual runtime protection, I can accept that.

> But right now, it's a f*cking disgrace that you are in denial about
> the fact that it's the *checking* that is broken, not the code, and
> are making excuses for shit.

I'm not in denial about that -- I think we just have very different
perspectives on this. I sent a bunch of patches to fix all the places
where there were false positives being found before this landed; I'm
not making excuses and I'm obviously interested in fixing it.

> So get rid of the BUG(), and get rid of the excuses.

I'll get it fixed up.

> We *know* this code is likely to find these kinds of "not really a
> bug, but the checker code does something we didn't used to do"
> situations.

Yup, agreed. We've already fixed a bunch of these, and while this
checking would catch some actual security vulnerabilities from the
past, I can see your point about its "newness" being too great a risk.


Kees Cook
Pixel Security