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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
        Jason Wang <jasowang@redhat.com>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Christoffer Dall <cdall@kernel.org>,
        Peter Maydel <peter.maydell@linaro.org>,
        Jean-Philippe Brucker <jean-philippe.brucker@arm.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.18 053/197] virtio: pci-legacy: Validate queue pfn
Date:   Thu, 13 Sep 2018 15:30:02 +0200
Message-Id: <20180913131843.651175379@linuxfoundation.org>
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References: <20180913131841.568116777@linuxfoundation.org>
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4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Suzuki K Poulose <suzuki.poulose@arm.com>

[ Upstream commit 69599206ea9a3f8f2e94d46580579cbf9d08ad6c ]

Legacy PCI over virtio uses a 32bit PFN for the queue. If the
queue pfn is too large to fit in 32bits, which we could hit on
arm64 systems with 52bit physical addresses (even with 64K page
size), we simply miss out a proper link to the other side of
the queue.

Add a check to validate the PFN, rather than silently breaking
the devices.

Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Marc Zyngier <marc.zyngier@arm.com>
Cc: Christoffer Dall <cdall@kernel.org>
Cc: Peter Maydel <peter.maydell@linaro.org>
Cc: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/virtio/virtio_pci_legacy.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- a/drivers/virtio/virtio_pci_legacy.c
+++ b/drivers/virtio/virtio_pci_legacy.c
@@ -122,6 +122,7 @@ static struct virtqueue *setup_vq(struct
 	struct virtqueue *vq;
 	u16 num;
 	int err;
+	u64 q_pfn;
 
 	/* Select the queue we're interested in */
 	iowrite16(index, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_SEL);
@@ -141,9 +142,17 @@ static struct virtqueue *setup_vq(struct
 	if (!vq)
 		return ERR_PTR(-ENOMEM);
 
+	q_pfn = virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT;
+	if (q_pfn >> 32) {
+		dev_err(&vp_dev->pci_dev->dev,
+			"platform bug: legacy virtio-mmio must not be used with RAM above 0x%llxGB\n",
+			0x1ULL << (32 + PAGE_SHIFT - 30));
+		err = -E2BIG;
+		goto out_del_vq;
+	}
+
 	/* activate the queue */
-	iowrite32(virtqueue_get_desc_addr(vq) >> VIRTIO_PCI_QUEUE_ADDR_SHIFT,
-		  vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+	iowrite32(q_pfn, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
 
 	vq->priv = (void __force *)vp_dev->ioaddr + VIRTIO_PCI_QUEUE_NOTIFY;
 
@@ -160,6 +169,7 @@ static struct virtqueue *setup_vq(struct
 
 out_deactivate:
 	iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
+out_del_vq:
 	vring_del_virtqueue(vq);
 	return ERR_PTR(err);
 }