can: esd_usb: esd_usb_read_bulk_callback(): fix URB memory leak

commit 5a4391b upstream.

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

In esd_usb_open(), the URBs for USB-in transfers are allocated, added to
the dev->rx_submitted anchor and submitted. In the complete callback
esd_usb_read_bulk_callback(), the URBs are processed and resubmitted. In
esd_usb_close() the URBs are freed by calling
usb_kill_anchored_urbs(&dev->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 esd_usb_close().

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

Fixes: 96d8e90 ("can: Add driver for esd CAN-USB/2 device")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260116-can_usb-fix-memory-leak-v2-2-4b8cb2915571@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/esd_usb.c

@@ -539,13 +539,20 @@ static void esd_usb_read_bulk_callback(struct urb *urb)
 			  urb->transfer_buffer, ESD_USB_RX_BUFFER_SIZE,
 			  esd_usb_read_bulk_callback, dev);
 
+	usb_anchor_urb(urb, &dev->rx_submitted);
+
 	retval = usb_submit_urb(urb, GFP_ATOMIC);
+	if (!retval)
+		return;
+
+	usb_unanchor_urb(urb);
+
 	if (retval == -ENODEV) {
 		for (i = 0; i < dev->net_count; i++) {
 			if (dev->nets[i])
 				netif_device_detach(dev->nets[i]->netdev);
 		}
-	} else if (retval) {
+	} else {
 		dev_err(dev->udev->dev.parent,
 			"failed resubmitting read bulk urb: %d\n", retval);
 	}