2015-08-07 12:54+0200, Paolo Bonzini: > The recent BlackHat 2015 presentation "The Memory Sinkhole" > mentions that the IDT limit is zeroed on entry to SMM.
Slide 64 of https://www.blackhat.com/docs/us-15/materials/us-15-Domas-The-Memory-Sinkhole-Unleashing-An-x86-Design-Flaw-Allowing-Universal-Privilege-Escalation.pdf > This is not documented, and must have changed some time after 2010 > (see http://www.ssi.gouv.fr/uploads/IMG/pdf/IT_Defense_2010_final.pdf). > KVM was not doing it, but the fix is easy. This patch also clears the IDT base. Fetching original IDT is better done from SMM saved state (and an anti-exploit based on comparing those two seems unlikely) so it should be fine, Reviewed-by: Radim Krčmář <rkrc...@redhat.com> > Signed-off-by: Paolo Bonzini <pbonz...@redhat.com> > --- That takes care of Attack 1. KVM is likely not vulnerable to attack 2 and 3 because of an emergent security feature. (A simple modification of kvm-unit-tests show that mapping APIC base on top of real code/data makes the APIC page hidden and I expect SMM memslot to behave similarly.) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
