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SubjectRe: [PATCH v3 01/20] virtio: mmio-v1: Validate queue PFN
On Fri, Jun 29, 2018 at 12:15:21PM +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>
> ---
> Changes since v2:
> - Change errno to -E2BIG
> ---
> 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..82cedc8 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");

How about:
"hypervisor bug: legacy virtio-mmio must not be used with more than 0x%llx Gigabytes of memory",
0x1ULL << (32 - 30) << PAGE_SHIFT

> + err = -E2BIG;
> + 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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