virtio-net: validate backend queue numbers against bus limitation

We don't validate the backend queue numbers against bus limitation,
this will easily crash qemu if it exceeds the limitation which will
hit the abort() in virtio_del_queue(). An example is trying to
starting a virtio-net device with 256 queues. E.g:

./qemu-system-x86_64 -netdev tap,id=hn0,queues=256 -device
virtio-net-pci,netdev=hn0

Fixing this by doing the validation and fail early.

Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: qemu-stable <qemu-stable@nongnu.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 27adcc5467cb784a8e64e916c70dbbda613274de..59f76bcf7676700fff53f2647c4b8f0a94d72b63 100644 (file)
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1588,6 +1588,13 @@ static void virtio_net_device_realize(DeviceState *dev, Error **errp)
     virtio_init(vdev, "virtio-net", VIRTIO_ID_NET, n->config_size);
 
     n->max_queues = MAX(n->nic_conf.peers.queues, 1);
+    if (n->max_queues * 2 + 1 > VIRTIO_PCI_QUEUE_MAX) {
+        error_setg(errp, "Invalid number of queues (= %" PRIu32 "), "
+                   "must be a postive integer less than %d.",
+                   n->max_queues, (VIRTIO_PCI_QUEUE_MAX - 1) / 2);
+        virtio_cleanup(vdev);
+        return;
+    }
     n->vqs = g_malloc0(sizeof(VirtIONetQueue) * n->max_queues);
     n->vqs[0].rx_vq = virtio_add_queue(vdev, 256, virtio_net_handle_rx);
     n->curr_queues = 1;