From: Maxim Levitsky <mlevitsk@xxxxxxxxxx> commit 16ae56d7e0528559bf8dc9070e3bfd8ba3de80df upstream. Make sure that KVM uses vmcb01 before freeing nested state, and warn if that is not the case. This is a minimal fix for CVE-2022-3344 making the kernel print a warning instead of a kernel panic. Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx> Message-Id: <20221103141351.50662-3-mlevitsk@xxxxxxxxxx> Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kvm/svm/nested.c | 3 +++ 1 file changed, 3 insertions(+) --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -919,6 +919,9 @@ void svm_free_nested(struct vcpu_svm *sv if (!svm->nested.initialized) return; + if (WARN_ON_ONCE(svm->vmcb != svm->vmcb01.ptr)) + svm_switch_vmcb(svm, &svm->vmcb01); + svm_vcpu_free_msrpm(svm->nested.msrpm); svm->nested.msrpm = NULL;
