linux-kernel - [PATCH V3] net: dsa: Add of_node_put() before break and return statements

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Message-Id: <20200823193054.29336-1-sylphrenadin@gmail.com>
Date:   Mon, 24 Aug 2020 01:00:54 +0530
From:   Sumera Priyadarsini <sylphrenadin@...il.com>
To:     davem@...emloft.net
Cc:     Julia.Lawall@...6.fr, andrew@...n.ch, sean.wang@...iatek.com,
        vivien.didelot@...il.com, f.fainelli@...il.com, kuba@...nel.org,
        matthias.bgg@...il.com, netdev@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Sumera Priyadarsini <sylphrenadin@...il.com>
Subject: [PATCH V3] net: dsa: Add of_node_put() before break and return statements

Every iteration of for_each_child_of_node() decrements
the reference count of the previous node, however when control
is transferred from the middle of the loop, as in the case of
a return or break or goto, there is no decrement thus ultimately
resulting in a memory leak.

Fix a potential memory leak in mt7530.c by inserting of_node_put()
before the break and return statements.

Issue found with Coccinelle.

---
Changes in v2:
	Add another of_node_put() in for_each_child_of_node() as pointed
out by Andrew.

Changes in v3:
	- Correct syntax errors
	- Modify commit message

---

Signed-off-by: Sumera Priyadarsini <sylphrenadin@...il.com>

Signed-off-by: Sumera Priyadarsini <sylphrenadin@...il.com>
---
 drivers/net/dsa/mt7530.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 8dcb8a49ab67..4b4701c69fe1 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -1326,14 +1326,17 @@ mt7530_setup(struct dsa_switch *ds)
 
 			if (phy_node->parent == priv->dev->of_node->parent) {
 				ret = of_get_phy_mode(mac_np, &interface);
-				if (ret && ret != -ENODEV)
+				if (ret && ret != -ENODEV) {
+					of_node_put(mac_np);
 					return ret;
+				}
 				id = of_mdio_parse_addr(ds->dev, phy_node);
 				if (id == 0)
 					priv->p5_intf_sel = P5_INTF_SEL_PHY_P0;
 				if (id == 4)
 					priv->p5_intf_sel = P5_INTF_SEL_PHY_P4;
 			}
+			of_node_put(mac_np);
 			of_node_put(phy_node);
 			break;
 		}
-- 
2.17.1