From: Maxim Levitsky <mlevitsk@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Paolo Bonzini <pbonzini@redhat.com>,
Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@redhat.com>,
Sean Christopherson <seanjc@google.com>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Maxim Levitsky <mlevitsk@redhat.com>,
stable@vger.kernel.org
Subject: [PATCH 4/4] KVM: x86: forcibly leave nested mode on vCPU reset
Date: Thu, 20 Oct 2022 12:30:55 +0300 [thread overview]
Message-ID: <20221020093055.224317-5-mlevitsk@redhat.com> (raw)
In-Reply-To: <20221020093055.224317-1-mlevitsk@redhat.com>
While not obivous, kvm_vcpu_reset leaves the nested mode by
clearing 'vcpu->arch.hflags' but it does so without all the
required housekeeping.
This makes SVM and VMX continue to use vmcs02/vmcb02 while
the cpu is not in nested mode.
In particular, in SVM code, it makes the 'svm_free_nested'
free the vmcb02, while still in use, which later triggers
use after free and a kernel crash.
This issue is assigned CVE-2022-3344
Cc: stable@vger.kernel.org
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
---
arch/x86/kvm/x86.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d86a8aae1471d3..313c4a6dc65e45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -11931,6 +11931,7 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
WARN_ON_ONCE(!init_event &&
(old_cr0 || kvm_read_cr3(vcpu) || kvm_read_cr4(vcpu)));
+ kvm_leave_nested(vcpu);
kvm_lapic_reset(vcpu, init_event);
vcpu->arch.hflags = 0;
--
2.26.3
next prev parent reply other threads:[~2022-10-20 9:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-20 9:30 [PATCH 0/4] nSVM: fix L0 crash if L2 has shutdown condtion which L1 doesn't intercept Maxim Levitsky
2022-10-20 9:30 ` [PATCH 1/4] KVM: x86: nSVM: leave nested mode on vCPU free Maxim Levitsky
2022-10-20 9:30 ` [PATCH 2/4] KVM: x86: nSVM: harden svm_free_nested against freeing vmcb02 while still in use Maxim Levitsky
2022-10-20 9:30 ` [PATCH 3/4] KVM: x86: add kvm_leave_nested Maxim Levitsky
2022-10-20 9:30 ` Maxim Levitsky [this message]
2022-10-20 15:33 ` [PATCH 4/4] KVM: x86: forcibly leave nested mode on vCPU reset Sean Christopherson
2022-10-25 13:37 ` Maxim Levitsky
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