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From:   Yanan Wang <wangyanan55@huawei.com>
To:     <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        Marc Zyngier <maz@kernel.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        James Morse <james.morse@arm.com>,
        "Julien Thierry" <julien.thierry.kdev@gmail.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Gavin Shan <gshan@redhat.com>,
        Quentin Perret <qperret@google.com>
CC:     <wanghaibin.wang@huawei.com>, <yezengruan@huawei.com>,
        <zhukeqian1@huawei.com>, <yuzenghui@huawei.com>,
        <jiangkunkun@huawei.com>, <wangjingyi11@huawei.com>,
        <lushenming@huawei.com>, Yanan Wang <wangyanan55@huawei.com>
Subject: [PATCH v2 1/3] KVM: arm64: Fix possible memory leak in kvm stage2
Date:   Wed, 2 Dec 2020 04:10:32 +0800
Message-ID: <20201201201034.116760-2-wangyanan55@huawei.com>
In-Reply-To: <20201201201034.116760-1-wangyanan55@huawei.com>
References: <20201201201034.116760-1-wangyanan55@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Precedence: bulk

When installing a new leaf pte onto an invalid ptep, we need to
get_page(ptep). When just updating a valid leaf ptep, we shouldn't
get_page(ptep). Incorrect page_count of translation tables might 
lead to memory leak, when unmapping a stage 2 memory range.

Signed-off-by: Yanan Wang <wangyanan55@huawei.com>
---
 arch/arm64/kvm/hyp/pgtable.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/arm64/kvm/hyp/pgtable.c b/arch/arm64/kvm/hyp/pgtable.c
index 0271b4a3b9fe..b232bdd142a6 100644
--- a/arch/arm64/kvm/hyp/pgtable.c
+++ b/arch/arm64/kvm/hyp/pgtable.c
@@ -470,6 +470,9 @@ static bool stage2_map_walker_try_leaf(u64 addr, u64 end, u32 level,
 	if (!kvm_block_mapping_supported(addr, end, phys, level))
 		return false;
 
+	if (kvm_pte_valid(*ptep))
+		put_page(virt_to_page(ptep));
+
 	if (kvm_set_valid_leaf_pte(ptep, phys, data->attr, level))
 		goto out;
 
-- 
2.19.1