From 53723b7be26ef31ad642ce5ffa8b42dec16db40e Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Mon, 16 Aug 2021 16:02:31 +0200 Subject: KVM: nSVM: avoid picking up unsupported bits from L2 in int_ctl (CVE-2021-3653) [ upstream commit 0f923e07124df069ba68d8bb12324398f4b6b709 ] * 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 Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'arch/x86/kvm/svm.c') diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 931acac69703..77bee73faebc 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -2564,7 +2564,11 @@ static bool nested_svm_vmrun(struct vcpu_svm *svm) svm->nested.intercept = nested_vmcb->control.intercept; svm_flush_tlb(&svm->vcpu); - svm->vmcb->control.int_ctl = nested_vmcb->control.int_ctl | V_INTR_MASKING_MASK; + svm->vmcb->control.int_ctl = nested_vmcb->control.int_ctl & + (V_TPR_MASK | V_IRQ_INJECTION_BITS_MASK); + + svm->vmcb->control.int_ctl |= V_INTR_MASKING_MASK; + if (nested_vmcb->control.int_ctl & V_INTR_MASKING_MASK) svm->vcpu.arch.hflags |= HF_VINTR_MASK; else -- cgit v1.2.3