diff options
| author | Maxim Levitsky <mlevitsk@redhat.com> | 2021-07-15 01:56:24 +0300 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2021-08-16 09:48:27 -0400 |
| commit | 0f923e07124df069ba68d8bb12324398f4b6b709 (patch) | |
| tree | e2fb5efdcf2bb619c2bd3cd6b04463bf6644a1c0 /arch | |
| parent | 6e949ddb0a6337817330c897e29ca4177c646f02 (diff) | |
KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl (CVE-2021-3653)
* Invert the mask of bits that we pick from L2 in
nested_vmcb02_prepare_control
* Invert and explicitly use VIRQ related bits bitmask in svm_clear_vintr
This fixes a security issue that allowed a malicious L1 to run L2 with
AVIC enabled, which allowed the L2 to exploit the uninitialized and enabled
AVIC to read/write the host physical memory at some offsets.
Fixes: 3d6368ef580a ("KVM: SVM: Add VMRUN handler")
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/include/asm/svm.h | 2 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/nested.c | 10 | ||||
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 9 |
3 files changed, 14 insertions, 7 deletions
diff --git a/arch/x86/include/asm/svm.h b/arch/x86/include/asm/svm.h index e322676039f4..b00dbc5fac2b 100644 --- a/arch/x86/include/asm/svm.h +++ b/arch/x86/include/asm/svm.h @@ -184,6 +184,8 @@ struct __attribute__ ((__packed__)) vmcb_control_area { #define V_IGN_TPR_SHIFT 20 #define V_IGN_TPR_MASK (1 << V_IGN_TPR_SHIFT) +#define V_IRQ_INJECTION_BITS_MASK (V_IRQ_MASK | V_INTR_PRIO_MASK | V_IGN_TPR_MASK) + #define V_INTR_MASKING_SHIFT 24 #define V_INTR_MASKING_MASK (1 << V_INTR_MASKING_SHIFT) diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 61738ff8ef33..28381ca5221c 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -503,7 +503,11 @@ static void nested_vmcb02_prepare_save(struct vcpu_svm *svm, struct vmcb *vmcb12 static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) { - const u32 mask = V_INTR_MASKING_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK; + const u32 int_ctl_vmcb01_bits = + V_INTR_MASKING_MASK | V_GIF_MASK | V_GIF_ENABLE_MASK; + + const u32 int_ctl_vmcb12_bits = V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK; + struct kvm_vcpu *vcpu = &svm->vcpu; /* @@ -535,8 +539,8 @@ static void nested_vmcb02_prepare_control(struct vcpu_svm *svm) vcpu->arch.l1_tsc_offset + svm->nested.ctl.tsc_offset; svm->vmcb->control.int_ctl = - (svm->nested.ctl.int_ctl & ~mask) | - (svm->vmcb01.ptr->control.int_ctl & mask); + (svm->nested.ctl.int_ctl & int_ctl_vmcb12_bits) | + (svm->vmcb01.ptr->control.int_ctl & int_ctl_vmcb01_bits); svm->vmcb->control.virt_ext = svm->nested.ctl.virt_ext; svm->vmcb->control.int_vector = svm->nested.ctl.int_vector; diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index e8ccab50ebf6..69639f9624f5 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1589,17 +1589,18 @@ static void svm_set_vintr(struct vcpu_svm *svm) static void svm_clear_vintr(struct vcpu_svm *svm) { - const u32 mask = V_TPR_MASK | V_GIF_ENABLE_MASK | V_GIF_MASK | V_INTR_MASKING_MASK; svm_clr_intercept(svm, INTERCEPT_VINTR); /* Drop int_ctl fields related to VINTR injection. */ - svm->vmcb->control.int_ctl &= mask; + svm->vmcb->control.int_ctl &= ~V_IRQ_INJECTION_BITS_MASK; if (is_guest_mode(&svm->vcpu)) { - svm->vmcb01.ptr->control.int_ctl &= mask; + svm->vmcb01.ptr->control.int_ctl &= ~V_IRQ_INJECTION_BITS_MASK; WARN_ON((svm->vmcb->control.int_ctl & V_TPR_MASK) != (svm->nested.ctl.int_ctl & V_TPR_MASK)); - svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl & ~mask; + + svm->vmcb->control.int_ctl |= svm->nested.ctl.int_ctl & + V_IRQ_INJECTION_BITS_MASK; } vmcb_mark_dirty(svm->vmcb, VMCB_INTR); |