linux-kernel - [PATCH 5.15 198/201] KVM: x86: fix typo in __try_cmpxchg

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Date:   Wed, 27 Jul 2022 18:11:42 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.15 198/201] KVM: x86: fix typo in __try_cmpxchg_user causing non-atomicness

From: Maxim Levitsky <mlevitsk@...hat.com>

commit 33fbe6befa622c082f7d417896832856814bdde0 upstream.

This shows up as a TDP MMU leak when running nested.  Non-working cmpxchg on L0
relies makes L1 install two different shadow pages under same spte, and one of
them is leaked.

Fixes: 1c2361f667f36 ("KVM: x86: Use __try_cmpxchg_user() to emulate atomic accesses")
Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
Message-Id: <20220512101420.306759-1-mlevitsk@...hat.com>
Reviewed-by: Sean Christopherson <seanjc@...gle.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@...hat.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/x86.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6933,7 +6933,7 @@ static int emulator_cmpxchg_emulated(str
 		goto emul_write;
 
 	hva = kvm_vcpu_gfn_to_hva(vcpu, gpa_to_gfn(gpa));
-	if (kvm_is_error_hva(addr))
+	if (kvm_is_error_hva(hva))
 		goto emul_write;
 
 	hva += offset_in_page(gpa);