[PATCH net-next] net: netsec: fix device_node reference leak on phy_np

[Yige Jiang <yigejiang86@gmail.com>]

netsec_of_probe() takes a reference on the PHY device_node with
of_parse_phandle() and stores it in priv->phy_np, but the driver never
drops it.  One device_node reference is leaked per probe, on the success
path as well as on every error path reached after netsec_of_probe().

Neither consumer takes ownership.  of_mdio_parse_addr() is a static
inline taking a const struct device_node * that only reads the "reg"
property.  of_phy_connect() borrows as well: of_phy_get_and_connect() in
drivers/net/mdio/of_mdio.c brackets its own call with of_node_get() at
:364 and of_node_put() at :373, which would be a double put if
of_phy_connect() consumed the reference.

The node is still in use at netsec_netdev_open() time, where it is
passed to of_phy_connect(), so it has device lifetime.  Release it at
the probe error label, which every failure path after the acquire
funnels through, and in netsec_remove().  Both releases precede
free_netdev(), since priv is netdev_priv(ndev).  The ACPI probe path
leaves priv->phy_np NULL and of_node_put(NULL) is a no-op.

There is no end-user visible symptom on currently supported platforms:
a device_node is only freed once OF_DYNAMIC is enabled and the node has
been detached, so on a static device tree the imbalance is inert.  It is
observable as a refcount that grows across bind/unbind cycles, and would
matter under device tree overlays.

Found by static analysis of reference acquire/release pairing rather
than from a runtime report.  No reproducer was produced and the change
has not been runtime tested; it is compile-tested only (arm64,
CONFIG_SNI_NETSEC=m via COMPILE_TEST).

Fixes: 533dd11a12f6 ("net: socionext: Add Synquacer NetSec driver")
Assisted-by: LLM
Signed-off-by: Yige Jiang <yigejiang86@gmail.com>
---
 drivers/net/ethernet/socionext/netsec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/socionext/netsec.c b/drivers/net/ethernet/socionext/netsec.c
index d14a6584473c8..79a0a324c921d 100644
--- a/drivers/net/ethernet/socionext/netsec.c
+++ b/drivers/net/ethernet/socionext/netsec.c
@@ -2149,6 +2149,7 @@ static int netsec_probe(struct platform_device *pdev)
 	pm_runtime_put_sync(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 free_ndev:
+	of_node_put(priv->phy_np);
 	free_netdev(ndev);
 	dev_err(&pdev->dev, "init failed\n");
 
@@ -2166,6 +2167,7 @@ static void netsec_remove(struct platform_device *pdev)
 	netif_napi_del(&priv->napi);
 
 	pm_runtime_disable(&pdev->dev);
+	of_node_put(priv->phy_np);
 	free_netdev(priv->ndev);
 }
 
-- 
2.50.1 (Apple Git-155)