can: mcba_usb: mcba_usb_read_bulk_callback(): fix URB memory leak

commit 710a752 upstream.

Fix similar memory leak as in commit 7352e1d ("can: gs_usb:
gs_usb_receive_bulk_callback(): fix URB memory leak").

In mcba_usb_probe() -> mcba_usb_start(), the URBs for USB-in transfers are
allocated, added to the priv->rx_submitted anchor and submitted. In the
complete callback mcba_usb_read_bulk_callback(), the URBs are processed and
resubmitted. In mcba_usb_close() -> mcba_urb_unlink() the URBs are freed by
calling usb_kill_anchored_urbs(&priv->rx_submitted).

However, this does not take into account that the USB framework unanchors
the URB before the complete function is called. This means that once an
in-URB has been completed, it is no longer anchored and is ultimately not
released in usb_kill_anchored_urbs().

Fix the memory leak by anchoring the URB in the
mcba_usb_read_bulk_callback()to the priv->rx_submitted anchor.

Fixes: 51f3baa ("can: mcba_usb: Add support for Microchip CAN BUS Analyzer")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260116-can_usb-fix-memory-leak-v2-4-4b8cb2915571@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: marckleinebudde

drivers/net/can/usb/mcba_usb.c

@@ -608,11 +608,17 @@ static void mcba_usb_read_bulk_callback(struct urb *urb)
 			  urb->transfer_buffer, MCBA_USB_RX_BUFF_SIZE,
 			  mcba_usb_read_bulk_callback, priv);
 
+	usb_anchor_urb(urb, &priv->rx_submitted);
+
 	retval = usb_submit_urb(urb, GFP_ATOMIC);
+	if (!retval)
+		return;
+
+	usb_unanchor_urb(urb);
 
 	if (retval == -ENODEV)
 		netif_device_detach(netdev);
-	else if (retval)
+	else
 		netdev_err(netdev, "failed resubmitting read bulk urb: %d\n",
 			   retval);
 }