| From cbdb967af3d54993f5814f1cee0ed311a055377d Mon Sep 17 00:00:00 2001 |
| From: Paolo Bonzini <pbonzini@redhat.com> |
| Date: Tue, 10 Nov 2015 09:14:39 +0100 |
| Subject: KVM: svm: unconditionally intercept #DB |
| |
| From: Paolo Bonzini <pbonzini@redhat.com> |
| |
| commit cbdb967af3d54993f5814f1cee0ed311a055377d upstream. |
| |
| This is needed to avoid the possibility that the guest triggers |
| an infinite stream of #DB exceptions (CVE-2015-8104). |
| |
| VMX is not affected: because it does not save DR6 in the VMCS, |
| it already intercepts #DB unconditionally. |
| |
| Reported-by: Jan Beulich <jbeulich@suse.com> |
| Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| arch/x86/kvm/svm.c | 14 +++----------- |
| 1 file changed, 3 insertions(+), 11 deletions(-) |
| |
| --- a/arch/x86/kvm/svm.c |
| +++ b/arch/x86/kvm/svm.c |
| @@ -1108,6 +1108,7 @@ static void init_vmcb(struct vcpu_svm *s |
| set_exception_intercept(svm, UD_VECTOR); |
| set_exception_intercept(svm, MC_VECTOR); |
| set_exception_intercept(svm, AC_VECTOR); |
| + set_exception_intercept(svm, DB_VECTOR); |
| |
| set_intercept(svm, INTERCEPT_INTR); |
| set_intercept(svm, INTERCEPT_NMI); |
| @@ -1642,20 +1643,13 @@ static void svm_set_segment(struct kvm_v |
| mark_dirty(svm->vmcb, VMCB_SEG); |
| } |
| |
| -static void update_db_bp_intercept(struct kvm_vcpu *vcpu) |
| +static void update_bp_intercept(struct kvm_vcpu *vcpu) |
| { |
| struct vcpu_svm *svm = to_svm(vcpu); |
| |
| - clr_exception_intercept(svm, DB_VECTOR); |
| clr_exception_intercept(svm, BP_VECTOR); |
| |
| - if (svm->nmi_singlestep) |
| - set_exception_intercept(svm, DB_VECTOR); |
| - |
| if (vcpu->guest_debug & KVM_GUESTDBG_ENABLE) { |
| - if (vcpu->guest_debug & |
| - (KVM_GUESTDBG_SINGLESTEP | KVM_GUESTDBG_USE_HW_BP)) |
| - set_exception_intercept(svm, DB_VECTOR); |
| if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) |
| set_exception_intercept(svm, BP_VECTOR); |
| } else |
| @@ -1761,7 +1755,6 @@ static int db_interception(struct vcpu_s |
| if (!(svm->vcpu.guest_debug & KVM_GUESTDBG_SINGLESTEP)) |
| svm->vmcb->save.rflags &= |
| ~(X86_EFLAGS_TF | X86_EFLAGS_RF); |
| - update_db_bp_intercept(&svm->vcpu); |
| } |
| |
| if (svm->vcpu.guest_debug & |
| @@ -3761,7 +3754,6 @@ static void enable_nmi_window(struct kvm |
| */ |
| svm->nmi_singlestep = true; |
| svm->vmcb->save.rflags |= (X86_EFLAGS_TF | X86_EFLAGS_RF); |
| - update_db_bp_intercept(vcpu); |
| } |
| |
| static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr) |
| @@ -4383,7 +4375,7 @@ static struct kvm_x86_ops svm_x86_ops = |
| .vcpu_load = svm_vcpu_load, |
| .vcpu_put = svm_vcpu_put, |
| |
| - .update_db_bp_intercept = update_db_bp_intercept, |
| + .update_db_bp_intercept = update_bp_intercept, |
| .get_msr = svm_get_msr, |
| .set_msr = svm_set_msr, |
| .get_segment_base = svm_get_segment_base, |