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    SubjectRe: [PATCH v2 2/9] KVM: x86: nSVM: harden svm_free_nested against freeing vmcb02 while still in use
    On 03/11/2022 14:13, Maxim Levitsky wrote:
    > 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@vger.kernel.org
    > Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>

    Reviewed-by: Liam Merwick <liam.merwick@oracle.com>


    > ---
    > arch/x86/kvm/svm/nested.c | 3 +++
    > 1 file changed, 3 insertions(+)
    >
    > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
    > index b258d6988f5dde..b74da40c1fc40c 100644
    > --- a/arch/x86/kvm/svm/nested.c
    > +++ b/arch/x86/kvm/svm/nested.c
    > @@ -1126,6 +1126,9 @@ void svm_free_nested(struct vcpu_svm *svm)
    > 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;
    >

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