linux-kernel - [PATCH 4.19 048/131] KVM: Properly check if "page" is valid in kvm_vcpu

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Date:   Tue, 28 Apr 2020 20:24:20 +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>,
        Ben Hutchings <ben.hutchings@...ethink.co.uk>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 048/131] 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")
Signed-off-by: KarimAllah Ahmed <karahmed@...zon.de>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Ben Hutchings <ben.hutchings@...ethink.co.uk>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 virt/kvm/kvm_main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 5b949aa273de5..33b288469c70c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1754,7 +1754,7 @@ void kvm_vcpu_unmap(struct kvm_vcpu *vcpu, struct kvm_host_map *map,
 	if (!map->hva)
 		return;
 
-	if (map->page)
+	if (map->page != KVM_UNMAPPED_PAGE)
 		kunmap(map->page);
 #ifdef CONFIG_HAS_IOMEM
 	else
-- 
2.20.1