From f6049f4483d61fa911a0693c2c48ce8308451d33 Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Fri, 26 Jul 2013 16:41:27 +0100 Subject: 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(-) (limited to 'hw') 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) -- cgit v1.2.3