| Message ID | 20210816140240.11399-12-pbonzini@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [5.4.y] KVM: nSVM: always intercept VMLOAD/VMSAVE when nested (CVE-2021-3656) | expand |
On Mon, Aug 16, 2021 at 04:02:40PM +0200, Paolo Bonzini wrote: > From: Maxim Levitsky <mlevitsk@redhat.com> > > [ upstream commit c7dfa4009965a9b2d7b329ee970eb8da0d32f0bc ] > > If L1 disables VMLOAD/VMSAVE intercepts, and doesn't enable > Virtual VMLOAD/VMSAVE (currently not supported for the nested hypervisor), > then VMLOAD/VMSAVE must operate on the L1 physical memory, which is only > possible by making L0 intercept these instructions. > > Failure to do so allowed the nested guest to run VMLOAD/VMSAVE unintercepted, > and thus read/write portions of the host physical memory. > > Fixes: 89c8a4984fc9 ("KVM: SVM: Enable Virtual VMLOAD VMSAVE feature") > > Suggested-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com> > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > --- > The above upstream SHA1 is still on its way to Linus > > arch/x86/kvm/svm.c | 3 +++ > 1 file changed, 3 insertions(+) 5.4, 5.10, and 5.13 versions now queued up and I'll do a new -rc release with them in it. I'll get to the others after dinner... thanks, greg k-h
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 515d0b03bf03..387c1dafee2a 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -516,6 +516,9 @@ static void recalc_intercepts(struct vcpu_svm *svm) c->intercept_dr = h->intercept_dr | g->intercept_dr; c->intercept_exceptions = h->intercept_exceptions | g->intercept_exceptions; c->intercept = h->intercept | g->intercept; + + c->intercept |= (1ULL << INTERCEPT_VMLOAD); + c->intercept |= (1ULL << INTERCEPT_VMSAVE); } static inline struct vmcb *get_host_vmcb(struct vcpu_svm *svm)