On Tue, Jan 9, 2018 at 5:04 AM, David Woodhouse <dw...@infradead.org> wrote: > On Mon, 2018-01-08 at 19:27 -0800, Andy Lutomirski wrote: >> > >> > If SMEP is not active, speculation can go anywhere, including to a user >> > controlled gadget which can reload any registers it needs, including >> > with immediate constants. >> >> I thought that, even on pre-SMEP hardware, the CPU wouldn't >> speculatively execute from NX pages. And PTI marks user memory NX >> in kernel mode. > > Hm, now that could be useful. > > Do *all* the KPTI backports (some of which are reimplementations rather > than strictly backports) mark user memory NX?
Yup. The KAISERish ports (4.9 and 4.4) have the same feature. -Kees -- Kees Cook Pixel Security
