releases/3.8.4/virtio-rng-disallow-multiple-device-registrations-fixes-crashes.patch

   1 From e84e7a56a3aa2963db506299e29a5f3f09377f9b Mon Sep 17 00:00:00 2001
   2 From: Amit Shah <amit.shah@redhat.com>
   3 Date: Fri, 8 Mar 2013 11:30:18 +1100
   4 Subject: virtio: rng: disallow multiple device registrations, fixes crashes
   5
   6 From: Amit Shah <amit.shah@redhat.com>
   7
   8 commit e84e7a56a3aa2963db506299e29a5f3f09377f9b upstream.
   9
  10 The code currently only supports one virtio-rng device at a time.
  11 Invoking guests with multiple devices causes the guest to blow up.
  12
  13 Check if we've already registered and initialised the driver.  Also
  14 cleanup in case of registration errors or hot-unplug so that a new
  15 device can be used.
  16
  17 Reported-by: Peter Krempa <pkrempa@redhat.com>
  18 Reported-by: <yunzheng@redhat.com>
  19 Signed-off-by: Amit Shah <amit.shah@redhat.com>
  20 Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
  21 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  22
  23 ---
  24  drivers/char/hw_random/virtio-rng.c |   13 +++++++++++--
  25  1 file changed, 11 insertions(+), 2 deletions(-)
  26
  27 --- a/drivers/char/hw_random/virtio-rng.c
  28 +++ b/drivers/char/hw_random/virtio-rng.c
  29 @@ -92,14 +92,22 @@ static int probe_common(struct virtio_de
  30  {
  31         int err;
  32
  33 +       if (vq) {
  34 +               /* We only support one device for now */
  35 +               return -EBUSY;
  36 +       }
  37         /* We expect a single virtqueue. */
  38         vq = virtio_find_single_vq(vdev, random_recv_done, "input");
  39 -       if (IS_ERR(vq))
  40 -               return PTR_ERR(vq);
  41 +       if (IS_ERR(vq)) {
  42 +               err = PTR_ERR(vq);
  43 +               vq = NULL;
  44 +               return err;
  45 +       }
  46
  47         err = hwrng_register(&virtio_hwrng);
  48         if (err) {
  49                 vdev->config->del_vqs(vdev);
  50 +               vq = NULL;
  51                 return err;
  52         }
  53
  54 @@ -112,6 +120,7 @@ static void remove_common(struct virtio_
  55         busy = false;
  56         hwrng_unregister(&virtio_hwrng);
  57         vdev->config->del_vqs(vdev);
  58 +       vq = NULL;
  59  }
  60
  61  static int virtrng_probe(struct virtio_device *vdev)