diff options
| author | Paolo Bonzini <pbonzini@redhat.com> | 2015-11-10 09:14:39 +0100 |
|---|---|---|
| committer | Zefan Li <lizefan@huawei.com> | 2016-03-21 09:17:55 +0800 |
| commit | 8f452aa305e1b8bec21c8ce191c4af2b0cc14067 (patch) | |
| tree | b44d2b36186117d72af1025dfe42248b6e5212d7 /arch | |
| parent | e1b6c3c95cbd3bb5947277e45cf4b7527020af11 (diff) | |
KVM: svm: unconditionally intercept #DB
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>
[bwh: Backported to 3.2, with thanks to Paolo:
- update_db_bp_intercept() was called update_db_intercept()
- The remaining call is in svm_guest_debug() rather than through svm_x86_ops]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kvm/svm.c | 14 |
1 files changed, 3 insertions, 11 deletions
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 56dd88ab65b8..6201ca0c9770 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1082,6 +1082,7 @@ static void init_vmcb(struct vcpu_svm *svm) 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); @@ -1637,20 +1638,13 @@ static void svm_set_segment(struct kvm_vcpu *vcpu, mark_dirty(svm->vmcb, VMCB_SEG); } -static void update_db_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 @@ -1668,7 +1662,7 @@ static void svm_guest_debug(struct kvm_vcpu *vcpu, struct kvm_guest_debug *dbg) mark_dirty(svm->vmcb, VMCB_DR); - update_db_intercept(vcpu); + update_bp_intercept(vcpu); } static void new_asid(struct vcpu_svm *svm, struct svm_cpu_data *sd) @@ -1742,7 +1736,6 @@ static int db_interception(struct vcpu_svm *svm) if (!(svm->vcpu.guest_debug & KVM_GUESTDBG_SINGLESTEP)) svm->vmcb->save.rflags &= ~(X86_EFLAGS_TF | X86_EFLAGS_RF); - update_db_intercept(&svm->vcpu); } if (svm->vcpu.guest_debug & @@ -3661,7 +3654,6 @@ static void enable_nmi_window(struct kvm_vcpu *vcpu) */ svm->nmi_singlestep = true; svm->vmcb->save.rflags |= (X86_EFLAGS_TF | X86_EFLAGS_RF); - update_db_intercept(vcpu); } static int svm_set_tss_addr(struct kvm *kvm, unsigned int addr) |