[PATCH 6.6 216/254] can: ems_usb: ems_usb_read_bulk_callback(): fix URB memory leak

Greg Kroah-Hartman
2026-01-28T15:40:10Z

From: Marc Kleine-Budde <mkl@pengutronix.de>

commit 0ce73a0eb5a27070957b67fd74059b6da89cc516 upstream.

Fix similar memory leak as in commit 7352e1d5932a ("can: gs_usb:
gs_usb_receive_bulk_callback(): fix URB memory leak").

In ems_usb_open(), the URBs for USB-in transfers are allocated, added to
the dev->rx_submitted anchor and submitted. In the complete callback
ems_usb_read_bulk_callback(), the URBs are processed and resubmitted. In
ems_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 ems_usb_close().

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

Fixes: 702171adeed3 ("ems_usb: Added support for EMS CPC-USB/ARM7 CAN/USB interface")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260116-can_usb-fix-memory-leak-v2-1-4b8cb2915571@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/can/usb/ems_usb.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/can/usb/ems_usb.c
+++ b/drivers/net/can/usb/ems_usb.c
@@ -486,11 +486,17 @@ resubmit_urb:
urb->transfer_buffer, RX_BUFFER_SIZE,
ems_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)
netif_device_detach(netdev);
- else if (retval)
+ else
netdev_err(netdev,
"failed resubmitting read bulk urb: %d\n", retval);
}