netdev - [PATCH net 6/7] can: mcba_usb: mcba_usb_read_bulk

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Message-ID: <20260116200323.366877-7-mkl@pengutronix.de>
Date: Fri, 16 Jan 2026 20:55:52 +0100
From: Marc Kleine-Budde <mkl@...gutronix.de>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	kuba@...nel.org,
	linux-can@...r.kernel.org,
	kernel@...gutronix.de,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	stable@...r.kernel.org
Subject: [PATCH net 6/7] can: mcba_usb: mcba_usb_read_bulk_callback(): fix URB memory leak

Fix similar memory leak as in commit 7352e1d5932a ("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: 51f3baad7de9 ("can: mcba_usb: Add support for Microchip CAN BUS Analyzer")
Cc: stable@...r.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@...gutronix.de>
---
 drivers/net/can/usb/mcba_usb.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/usb/mcba_usb.c b/drivers/net/can/usb/mcba_usb.c
index 41c0a1c399bf..04170326dc7e 100644
--- a/drivers/net/can/usb/mcba_usb.c
+++ b/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);
 }
-- 
2.51.0