Re: [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message

[Borislav Petkov]

On Tue, Nov 03, 2020 at 07:11:15PM +0100, Oleg Nesterov wrote:
> > I'm thinking copy_code() should not use copy_from_user_nmi() if former
> > can be called in non-atomic context too.
> 
> I understand, but why do you think this makes sense?

Because the copy_from_user_nmi()'s name tells me that it is at least
supposed to be called in atomic context. At least this is how I
understand it. And in atomic context regs is supposed to belong to
current, right?

So I kinda agree with what you're proposing but if copy_from_user_nmi()
can be "tricked" into reading off from the weeds, then there should be
a big fat warning above it at least so that users are warned to do the
appropriate checks.

Or there should be another wrapper around it which does the
regs-belongs-to-current checks, etc and copy_code() should use that
wrapper...

AFAICT at least.

-- 
Regards/Gruss,
    Boris.

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