net: hso: check for allocation failure in hso_create_bulk_serial_device()

In current kernels, small allocations never actually fail so this
patch shouldn't affect runtime.

Originally this error handling code written with the idea that if
the "serial->tiocmget" allocation failed, then we would continue
operating instead of bailing out early.  But in later years we added
an unchecked dereference on the next line.

	serial->tiocmget->serial_state_notification = kzalloc();
        ^^^^^^^^^^^^^^^^^^

Since these allocations are never going fail in real life, this is
mostly a philosophical debate, but I think bailing out early is the
correct behavior that the user would want.  And generally it's safer to
bail as soon an error happens.

Fixes: af0de1303c4e ("usb: hso: obey DMA rules in tiocmget")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/usb/hso.c b/drivers/net/usb/hso.c
index 3ef4b28..260f850 100644 (file)
--- a/drivers/net/usb/hso.c
+++ b/drivers/net/usb/hso.c
@@ -2618,29 +2618,28 @@ static struct hso_device *hso_create_bulk_serial_device(
                num_urbs = 2;
                serial->tiocmget = kzalloc(sizeof(struct hso_tiocmget),
                                           GFP_KERNEL);
+               if (!serial->tiocmget)
+                       goto exit;
                serial->tiocmget->serial_state_notification
                        = kzalloc(sizeof(struct hso_serial_state_notification),
                                           GFP_KERNEL);
-               /* it isn't going to break our heart if serial->tiocmget
-                *  allocation fails don't bother checking this.
-                */
-               if (serial->tiocmget && serial->tiocmget->serial_state_notification) {
-                       tiocmget = serial->tiocmget;
-                       tiocmget->endp = hso_get_ep(interface,
-                                                   USB_ENDPOINT_XFER_INT,
-                                                   USB_DIR_IN);
-                       if (!tiocmget->endp) {
-                               dev_err(&interface->dev, "Failed to find INT IN ep\n");
-                               goto exit;
-                       }
-
-                       tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
-                       if (tiocmget->urb) {
-                               mutex_init(&tiocmget->mutex);
-                               init_waitqueue_head(&tiocmget->waitq);
-                       } else
-                               hso_free_tiomget(serial);
+               if (!serial->tiocmget->serial_state_notification)
+                       goto exit;
+               tiocmget = serial->tiocmget;
+               tiocmget->endp = hso_get_ep(interface,
+                                           USB_ENDPOINT_XFER_INT,
+                                           USB_DIR_IN);
+               if (!tiocmget->endp) {
+                       dev_err(&interface->dev, "Failed to find INT IN ep\n");
+                       goto exit;
                }
+
+               tiocmget->urb = usb_alloc_urb(0, GFP_KERNEL);
+               if (tiocmget->urb) {
+                       mutex_init(&tiocmget->mutex);
+                       init_waitqueue_head(&tiocmget->waitq);
+               } else
+                       hso_free_tiomget(serial);
        }
        else
                num_urbs = 1;