Messages in this thread | | | Date | Mon, 2 Nov 2020 19:39:38 +0100 | From | Borislav Petkov <> | Subject | Re: How should we handle illegal task FPU state? |
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On Thu, Oct 01, 2020 at 03:04:48PM -0700, Andy Lutomirski wrote: > On Thu, Oct 1, 2020 at 2:50 PM Dave Hansen <dave.hansen@intel.com> wrote: > > I'm not sure we should ever keep running userspace after an XRSTOR* > > failure. For MPX, this might have provided a nice, additional vector > > for an attacker to turn off MPX. Same for pkeys if we didn't correctly > > differentiate between the hardware init state versus the "software init" > > state that we keep in init_task. > > > > What's the advantage of letting userspace keep running after we init its > > state? That it _might_ be able to recover? > > I suppose we can kill userspace and change that behavior only if > someone complains. I still think it would be polite to try to dump > core, but that could be tricky with the current code structure. I'll > try to whip up a patch. Maybe I'll add a debugfs file to trash MXCSR > for testing.
Just for the record, I like this: safe and simple. We can always do smarter shenanigans later, if at all needed, that is.
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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