linux-kernel - [PATCH 3/5] net: renesas: rswitch: avoid use-after-put for a device tree node

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Message-Id: <20241202134904.3882317-4-nikita.yoush@cogentembedded.com>
Date: Mon,  2 Dec 2024 18:49:02 +0500
From: Nikita Yushchenko <nikita.yoush@...entembedded.com>
To: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>,
	Andrew Lunn <andrew@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>,
	Paolo Abeni <pabeni@...hat.com>,
	Geert Uytterhoeven <geert+renesas@...der.be>
Cc: netdev@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Michael Dege <michael.dege@...esas.com>,
	Christian Mardmoeller <christian.mardmoeller@...esas.com>,
	Dennis Ostermann <dennis.ostermann@...esas.com>,
	Nikita Yushchenko <nikita.yoush@...entembedded.com>
Subject: [PATCH 3/5] net: renesas: rswitch: avoid use-after-put for a device tree node

The device tree node saved in the rswitch_device structure is used at
several driver locations. So passing this node to of_node_put() after
the first use is wrong.

Move of_node_put() for this node to exit paths.

Fixes: b46f1e579329 ("net: renesas: rswitch: Simplify struct phy * handling")
Signed-off-by: Nikita Yushchenko <nikita.yoush@...entembedded.com>
---
 drivers/net/ethernet/renesas/rswitch.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
index 3ad5858d3cdd..779c05b8e05f 100644
--- a/drivers/net/ethernet/renesas/rswitch.c
+++ b/drivers/net/ethernet/renesas/rswitch.c
@@ -1891,7 +1891,6 @@ static int rswitch_device_alloc(struct rswitch_private *priv, unsigned int index
 	rdev->np_port = rswitch_get_port_node(rdev);
 	rdev->disabled = !rdev->np_port;
 	err = of_get_ethdev_address(rdev->np_port, ndev);
-	of_node_put(rdev->np_port);
 	if (err) {
 		if (is_valid_ether_addr(rdev->etha->mac_addr))
 			eth_hw_addr_set(ndev, rdev->etha->mac_addr);
@@ -1921,6 +1920,7 @@ static int rswitch_device_alloc(struct rswitch_private *priv, unsigned int index
 
 out_rxdmac:
 out_get_params:
+	of_node_put(rdev->np_port);
 	netif_napi_del(&rdev->napi);
 	free_netdev(ndev);
 
@@ -1934,6 +1934,7 @@ static void rswitch_device_free(struct rswitch_private *priv, unsigned int index
 
 	rswitch_txdmac_free(ndev);
 	rswitch_rxdmac_free(ndev);
+	of_node_put(rdev->np_port);
 	netif_napi_del(&rdev->napi);
 	free_netdev(ndev);
 }
-- 
2.39.5