Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64

Jiri Kosina
2018-11-29T14:42:28Z

On Thu, 29 Nov 2018, Peter Zijlstra wrote:

> > int3 isn’t IST anymore, so the int3 instruction conditionally
> > subtracts 8 from RSP and then pushes SS, etc. So my email was
> > obviously wrong wrt “cs”, but you’re still potentially overwriting the
> > int3 IRET frame.
>
> ARGH!..
>
> can't we 'fix' that again? The alternative is moving that IRET-frame and
> fixing everything up, which is going to be fragile, ugly and such
> things more.
>
> Commit d8ba61ba58c8 ("x86/entry/64: Don't use IST entry for #BP stack")
> doesn't list any strong reasons for why it should NOT be an IST.

It's CVE-2018-8897.

--
Jiri Kosina
SUSE Labs