linux-kernel - [PATCH 5.2 331/413] KVM: Properly check if "page" is valid in kvm_vcpu

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Date:   Wed, 24 Jul 2019 21:20:22 +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, KarimAllah Ahmed <karahmed@...zon.de>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: [PATCH 5.2 331/413] KVM: Properly check if "page" is valid in kvm_vcpu_unmap

From: KarimAllah Ahmed <karahmed@...zon.de>

commit b614c6027896ff9ad6757122e84760d938cab15e upstream.

The field "page" is initialized to KVM_UNMAPPED_PAGE when it is not used
(i.e. when the memory lives outside kernel control). So this check will
always end up using kunmap even for memremap regions.

Fixes: e45adf665a53 ("KVM: Introduce a new guest mapping API")
Cc: stable@...r.kernel.org
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 virt/kvm/kvm_main.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1790,7 +1790,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcp
 	if (!map->hva)
 		return;
 
-	if (map->page)
+	if (map->page != KVM_UNMAPPED_PAGE)
 		kunmap(map->page);
 #ifdef CONFIG_HAS_IOMEM
 	else