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    SubjectRe: [PATCH v2 01/17] virtio: mmio-v1: Validate queue PFN
    On Tue, Mar 27, 2018 at 02:15:11PM +0100, Suzuki K Poulose wrote:
    > virtio-mmio with virtio-v1 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>

    OK - seems harmless so I will queue this.
    But I really think effort should be spent on
    adding v1.0 support in QEMU.

    > ---
    > drivers/virtio/virtio_mmio.c | 18 ++++++++++++++++--
    > 1 file changed, 16 insertions(+), 2 deletions(-)
    >
    > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
    > index 67763d3..b2f9b5c 100644
    > --- a/drivers/virtio/virtio_mmio.c
    > +++ b/drivers/virtio/virtio_mmio.c
    > @@ -397,9 +397,21 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
    > /* Activate the queue */
    > writel(virtqueue_get_vring_size(vq), vm_dev->base + VIRTIO_MMIO_QUEUE_NUM);
    > if (vm_dev->version == 1) {
    > + u64 q_pfn = virtqueue_get_desc_addr(vq) >> PAGE_SHIFT;
    > +
    > + /*
    > + * virtio-mmio v1 uses a 32bit QUEUE PFN. If we have something
    > + * that doesn't fit in 32bit, fail the setup rather than
    > + * pretending to be successful.
    > + */
    > + if (q_pfn >> 32) {
    > + dev_err(&vdev->dev, "virtio-mmio: queue address too large\n");
    > + err = -ENOMEM;
    > + goto error_bad_pfn;
    > + }
    > +
    > writel(PAGE_SIZE, vm_dev->base + VIRTIO_MMIO_QUEUE_ALIGN);
    > - writel(virtqueue_get_desc_addr(vq) >> PAGE_SHIFT,
    > - vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
    > + writel(q_pfn, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
    > } else {
    > u64 addr;
    >
    > @@ -430,6 +442,8 @@ static struct virtqueue *vm_setup_vq(struct virtio_device *vdev, unsigned index,
    >
    > return vq;
    >
    > +error_bad_pfn:
    > + vring_del_virtqueue(vq);
    > error_new_virtqueue:
    > if (vm_dev->version == 1) {
    > writel(0, vm_dev->base + VIRTIO_MMIO_QUEUE_PFN);
    > --
    > 2.7.4

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