queue-4.19/s390-virtio-handle-find-on-invalid-queue-gracefully.patch

   1 From 3438b2c039b4bf26881786a1f3450f016d66ad11 Mon Sep 17 00:00:00 2001
   2 From: Halil Pasic <pasic@linux.ibm.com>
   3 Date: Mon, 21 Jan 2019 13:19:43 +0100
   4 Subject: s390/virtio: handle find on invalid queue gracefully
   5
   6 From: Halil Pasic <pasic@linux.ibm.com>
   7
   8 commit 3438b2c039b4bf26881786a1f3450f016d66ad11 upstream.
   9
  10 A queue with a capacity of zero is clearly not a valid virtio queue.
  11 Some emulators report zero queue size if queried with an invalid queue
  12 index. Instead of crashing in this case let us just return -ENOENT. To
  13 make that work properly, let us fix the notifier cleanup logic as well.
  14
  15 Cc: stable@vger.kernel.org
  16 Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
  17 Signed-off-by: Cornelia Huck <cohuck@redhat.com>
  18 Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20
  21 ---
  22  drivers/s390/virtio/virtio_ccw.c |    4 +++-
  23  1 file changed, 3 insertions(+), 1 deletion(-)
  24
  25 --- a/drivers/s390/virtio/virtio_ccw.c
  26 +++ b/drivers/s390/virtio/virtio_ccw.c
  27 @@ -272,6 +272,8 @@ static void virtio_ccw_drop_indicators(s
  28  {
  29         struct virtio_ccw_vq_info *info;
  30
  31 +       if (!vcdev->airq_info)
  32 +               return;
  33         list_for_each_entry(info, &vcdev->virtqueues, node)
  34                 drop_airq_indicator(info->vq, vcdev->airq_info);
  35  }
  36 @@ -413,7 +415,7 @@ static int virtio_ccw_read_vq_conf(struc
  37         ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_READ_VQ_CONF);
  38         if (ret)
  39                 return ret;
  40 -       return vcdev->config_block->num;
  41 +       return vcdev->config_block->num ?: -ENOENT;
  42  }
  43
  44  static void virtio_ccw_del_vq(struct virtqueue *vq, struct ccw1 *ccw)