net: gianfar: fix device leak when querying time stamp info

commit da717540acd34e5056e3fa35791d50f6b3303f55 upstream.

Make sure to drop the reference to the ptp device taken by
of_find_device_by_node() when querying the time stamping capabilities.

Note that holding a reference to the ptp device does not prevent its
driver data from going away.

Fixes: 7349a74ea75c ("net: ethernet: gianfar_ethtool: get phc index through drvdata")
Cc: stable@vger.kernel.org	# 4.18
Cc: Yangbo Lu <yangbo.lu@nxp.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250725171213.880-4-johan@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/freescale/gianfar_ethtool.c b/drivers/net/ethernet/freescale/gianfar_ethtool.c
index 781d92e703cb3dc3d93d80ee16ccd29222634b83..c9992ed4e30135a8a72c285ecf561fbed294cbfe 100644 (file)
--- a/drivers/net/ethernet/freescale/gianfar_ethtool.c
+++ b/drivers/net/ethernet/freescale/gianfar_ethtool.c
@@ -1466,8 +1466,10 @@ static int gfar_get_ts_info(struct net_device *dev,
        if (ptp_node) {
                ptp_dev = of_find_device_by_node(ptp_node);
                of_node_put(ptp_node);
-               if (ptp_dev)
+               if (ptp_dev) {
                        ptp = platform_get_drvdata(ptp_dev);
+                       put_device(&ptp_dev->dev);
+               }
        }
 
        if (ptp)