[ 03/75] virtio: rng: disallow multiple device registrations, fixes crashes

Greg Kroah-Hartman
2013-03-18T21:06:39Z

From: Amit Shah <amit.shah@redhat.com>

commit e84e7a56a3aa2963db506299e29a5f3f09377f9b upstream.

The code currently only supports one virtio-rng device at a time.
Invoking guests with multiple devices causes the guest to blow up.

Check if we've already registered and initialised the driver. Also
cleanup in case of registration errors or hot-unplug so that a new
device can be used.

Reported-by: Peter Krempa <pkrempa@redhat.com>
Reported-by: <yunzheng@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/char/hw_random/virtio-rng.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)

--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -92,14 +92,22 @@ static int probe_common(struct virtio_de
{
int err;

+ if (vq) {
+ /* We only support one device for now */
+ return -EBUSY;
+ }
/* We expect a single virtqueue. */
vq = virtio_find_single_vq(vdev, random_recv_done, "input");
- if (IS_ERR(vq))
- return PTR_ERR(vq);
+ if (IS_ERR(vq)) {
+ err = PTR_ERR(vq);
+ vq = NULL;
+ return err;
+ }

err = hwrng_register(&virtio_hwrng);
if (err) {
vdev->config->del_vqs(vdev);
+ vq = NULL;
return err;
}

@@ -112,6 +120,7 @@ static void remove_common(struct virtio_
busy = false;
hwrng_unregister(&virtio_hwrng);
vdev->config->del_vqs(vdev);
+ vq = NULL;
}

static int virtrng_probe(struct virtio_device *vdev)