From f6049f4483d61fa911a0693c2c48ce8308451d33 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Fri, 26 Jul 2013 16:41:27 +0100 Subject: [PATCH 1/2] hw/virtio/virtio: Don't allow guests to add/remove queues A queue size of 0 is used to indicate a nonexistent queue, so don't allow the guest to flip a queue between zero-size and non-zero-size. Don't permit setting of negative queue sizes either. Signed-off-by: Peter Maydell Message-id: 1374853288-9912-2-git-send-email-peter.maydell@linaro.org Reviewed-by: Michael S. Tsirkin --- hw/virtio/virtio.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 09f62c6c70..60653f764e 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -673,10 +673,16 @@ hwaddr virtio_queue_get_addr(VirtIODevice *vdev, int n) void virtio_queue_set_num(VirtIODevice *vdev, int n, int num) { - if (num <= VIRTQUEUE_MAX_SIZE) { - vdev->vq[n].vring.num = num; - virtqueue_init(&vdev->vq[n]); + /* Don't allow guest to flip queue between existent and + * nonexistent states, or to set it to an invalid size. + */ + if (!!num != !!vdev->vq[n].vring.num || + num > VIRTQUEUE_MAX_SIZE || + num < 0) { + return; } + vdev->vq[n].vring.num = num; + virtqueue_init(&vdev->vq[n]); } int virtio_queue_get_num(VirtIODevice *vdev, int n) From f7b803b377f74f7e109559e8e64f04c4c1fcd86b Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Fri, 26 Jul 2013 16:41:28 +0100 Subject: [PATCH 2/2] hw/virtio/virtio-mmio: Make QueueNumMax read 0 for unavailable queues The virtio-mmio spec says that QueueNumMax must read zero for queues which are unavailable; implement this, rather than always returning VIRTQUEUE_MAX_SIZE. Signed-off-by: Peter Maydell Message-id: 1374853288-9912-3-git-send-email-peter.maydell@linaro.org Reviewed-by: Michael S. Tsirkin --- hw/virtio/virtio-mmio.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/hw/virtio/virtio-mmio.c b/hw/virtio/virtio-mmio.c index 88cf994b97..4bd29533f3 100644 --- a/hw/virtio/virtio-mmio.c +++ b/hw/virtio/virtio-mmio.c @@ -151,6 +151,9 @@ static uint64_t virtio_mmio_read(void *opaque, hwaddr offset, unsigned size) } return proxy->host_features; case VIRTIO_MMIO_QUEUENUMMAX: + if (!virtio_queue_get_num(vdev, vdev->queue_sel)) { + return 0; + } return VIRTQUEUE_MAX_SIZE; case VIRTIO_MMIO_QUEUEPFN: return virtio_queue_get_addr(vdev, vdev->queue_sel)