Fix -usbdevice crash

If -usbdevice is used on a machine with no USB busses, usb_create
will fail and return NULL.  Patch below handles this failure gracefully
rather than crashing when we try to init the device.

Signed-off-by: Paul Brook <paul@codesourcery.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/hw/usb-net.c b/hw/usb-net.c
index cfd2f62..6875f11 100644
--- a/hw/usb-net.c
+++ b/hw/usb-net.c
@@ -1491,6 +1491,9 @@ static USBDevice *usb_net_init(const char *cmdline)
     }
 
     dev = usb_create(NULL /* FIXME */, "usb-net");
+    if (!dev) {
+        return NULL;
+    }
     qdev_set_nic_properties(&dev->qdev, &nd_table[idx]);
     qdev_init_nofail(&dev->qdev);
     return dev;