virtio-rng: make device ready before making request

Current virtio-rng does a entropy request before DRIVER_OK, this
violates the spec:

virtio spec requires that all drivers set DRIVER_OK
before using devices.

Further, kernel will ignore the interrupt after commit
8b4ec69d7e09 ("virtio: harden vring IRQ").

Fixing this by making device ready before the request.

Cc: stable@vger.kernel.org
Fixes: 8b4ec69d7e09 ("virtio: harden vring IRQ")
Fixes: f7f510ec1957 ("virtio: An entropy device, as suggested by hpa.")
Reported-and-tested-by: syzbot+5b59d6d459306a556f54@syzkaller.appspotmail.com
Signed-off-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20220608061422.38437-1-jasowang@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>

diff --git a/drivers/char/hw_random/virtio-rng.c b/drivers/char/hw_random/virtio-rng.c
index e856df7e285c73c57e6ac9334c6e03831c12b1fb..a6f3a8a2aca6d1c9091a21da56d3efea38ba74e9 100644 (file)
--- a/drivers/char/hw_random/virtio-rng.c
+++ b/drivers/char/hw_random/virtio-rng.c
@@ -159,6 +159,8 @@ static int probe_common(struct virtio_device *vdev)
                goto err_find;
        }
 
+       virtio_device_ready(vdev);
+
        /* we always have a pending entropy request */
        request_entropy(vi);