Re: [PATCH v4 02/20] virtio: pci-legacy: Validate queue pfn

Michael S. Tsirkin
2018-07-22T15:40:52Z

On Wed, Jul 18, 2018 at 10:18:45AM +0100, Suzuki K Poulose wrote:
> 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>

Acked-by: Michael S. Tsirkin <mst@redhat.com>

I assume this will be merged through some other tree.

> ---
> Changes since v2:
> - Change errno to -E2BIG
> ---
> drivers/virtio/virtio_pci_legacy.c | 14 ++++++++++++--
> 1 file changed, 12 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/virtio/virtio_pci_legacy.c b/drivers/virtio/virtio_pci_legacy.c
> index 2780886..de062fb 100644
> --- a/drivers/virtio/virtio_pci_legacy.c
> +++ b/drivers/virtio/virtio_pci_legacy.c
> @@ -122,6 +122,7 @@ static struct virtqueue *setup_vq(struct virtio_pci_device *vp_dev,
> 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 virtio_pci_device *vp_dev,
> 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 virtio_pci_device *vp_dev,
>
> out_deactivate:
> iowrite32(0, vp_dev->ioaddr + VIRTIO_PCI_QUEUE_PFN);
> +out_del_vq:
> vring_del_virtqueue(vq);
> return ERR_PTR(err);
> }
> --
> 2.7.4