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KVM: x86: nSVM: harden svm_free_nested against freeing vmcb02 while still in use

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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@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20221103141351.50662-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Maxim Levitsky
2022-11-03 16:13:44 +02:00
committed by Greg Kroah-Hartman
parent 6425c590d0
commit 3e87cb0caa
1 changed files with 3 additions and 0 deletions
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3
arch/x86/kvm/svm/nested.c
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@@ -919,6 +919,9 @@ void svm_free_nested(struct vcpu_svm *svm)
if (!svm->nested.initialized) if (!svm->nested.initialized)
return; return;
if (WARN_ON_ONCE(svm->vmcb != svm->vmcb01.ptr))
svm_switch_vmcb(svm, &svm->vmcb01);
svm_vcpu_free_msrpm(svm->nested.msrpm); svm_vcpu_free_msrpm(svm->nested.msrpm);
svm->nested.msrpm = NULL; svm->nested.msrpm = NULL;