can: gs_usb: gs_usb_receive_bulk_callback(): fix URB memory leak

In gs_can_open(), the URBs for USB-in transfers are allocated, added to the
parent->rx_submitted anchor and submitted. In the complete callback
gs_usb_receive_bulk_callback(), the URB is processed and resubmitted. In
gs_can_close() the URBs are freed by calling
usb_kill_anchored_urbs(parent->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 gs_can_close().

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

Fixes: d08e973a77 ("can: gs_usb: Added support for the GS_USB CAN devices")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260105-gs_usb-fix-memory-leak-v2-1-cc6ed6438034@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/usb/gs_usb.c

@@ -751,6 +751,8 @@ resubmit_urb:
 			  hf, parent->hf_size_rx,
 			  gs_usb_receive_bulk_callback, parent);
 
+	usb_anchor_urb(urb, &parent->rx_submitted);
+
 	rc = usb_submit_urb(urb, GFP_ATOMIC);
 
 	/* USB failure take down all interfaces */