linux-kernel - [PATCH v3] net: dsa: mv88e6xxx: Fix refcount leak in mv88e6xxx_mdios

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Date:   Thu, 26 May 2022 18:52:08 +0400
From:   Miaoqian Lin <linmq006@...il.com>
To:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     linmq006@...il.com
Subject: [PATCH v3] net: dsa: mv88e6xxx: Fix refcount leak in mv88e6xxx_mdios_register

of_get_child_by_name() returns a node pointer with refcount
incremented, we should use of_node_put() on it when done.

mv88e6xxx_mdio_register() pass the device node to of_mdiobus_register().
We don't need the device node after it.

Add missing of_node_put() to avoid refcount leak.

Fixes: a3c53be55c95 ("net: dsa: mv88e6xxx: Support multiple MDIO busses")
Signed-off-by: Miaoqian Lin <linmq006@...il.com>
---
changes in v2:
- Add fixes tag.
changes in v3:
- Move of_node_put() statement to cover normal path.
- Update commit message.

I do cross-check to determine we should release the node after
of_mdiobus_register(), refer to functions like lan78xx_mdio_init(),
ave_init() and ag71xx_mdio_probe().

v1 link: https://lore.kernel.org/r/20220526083748.39816-1-linmq006@gmail.com/
v2 link: https://lore.kernel.org/all/20220526112415.13835-1-linmq006@gmail.com/
---
 drivers/net/dsa/mv88e6xxx/chip.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index 5d2c57a7c708..0b49d243e00b 100644
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -3960,6 +3960,7 @@ static int mv88e6xxx_mdios_register(struct mv88e6xxx_chip *chip,
 	 */
 	child = of_get_child_by_name(np, "mdio");
 	err = mv88e6xxx_mdio_register(chip, child, false);
+	of_node_put(child);
 	if (err)
 		return err;
 
-- 
2.25.1