Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Sasha Levin <sashal@kernel.org>
To:     stable@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Johan Hovold <johan@kernel.org>, Andrew Lunn <andrew@lunn.ch>,
        Giuseppe Cavallaro <peppe.cavallaro@st.com>,
        Alexandre Torgue <alexandre.torgue@st.com>,
        Jose Abreu <joabreu@synopsys.com>,
        "David S . Miller" <davem@davemloft.net>,
        Rob Herring <robh@kernel.org>, Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.19 087/146] net: stmmac: dwmac-sun8i: fix OF child-node lookup
Date:   Wed, 31 Oct 2018 19:04:42 -0400
Message-Id: <20181031230541.28822-87-sashal@kernel.org>
In-Reply-To: <20181031230541.28822-1-sashal@kernel.org>
References: <20181031230541.28822-1-sashal@kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Johan Hovold <johan@kernel.org>

[ Upstream commit ac63043d8cb5503c7e0fe110f947eacf2663804e ]

Use the new of_get_compatible_child() helper to lookup the mdio-internal
child node instead of using of_find_compatible_node(), which searches
the entire tree from a given start node and thus can return an unrelated
(i.e. non-child) node.

This also addresses a potential use-after-free (e.g. after probe
deferral) as the tree-wide helper drops a reference to its first
argument (i.e. the mdio-mux node). Fortunately, this was inadvertently
balanced by a failure to drop the mdio-mux reference after lookup.

While at it, also fix the related mdio-internal- and phy-node reference
leaks.

Fixes: 634db83b8265 ("net: stmmac: dwmac-sun8i: Handle integrated/external MDIOs")
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Alexandre Torgue <alexandre.torgue@st.com>
Cc: Jose Abreu <joabreu@synopsys.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index f9a61f90cfbc..0f660af01a4b 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -714,8 +714,9 @@ static int get_ephy_nodes(struct stmmac_priv *priv)
 		return -ENODEV;
 	}
 
-	mdio_internal = of_find_compatible_node(mdio_mux, NULL,
+	mdio_internal = of_get_compatible_child(mdio_mux,
 						"allwinner,sun8i-h3-mdio-internal");
+	of_node_put(mdio_mux);
 	if (!mdio_internal) {
 		dev_err(priv->device, "Cannot get internal_mdio node\n");
 		return -ENODEV;
@@ -729,13 +730,20 @@ static int get_ephy_nodes(struct stmmac_priv *priv)
 		gmac->rst_ephy = of_reset_control_get_exclusive(iphynode, NULL);
 		if (IS_ERR(gmac->rst_ephy)) {
 			ret = PTR_ERR(gmac->rst_ephy);
-			if (ret == -EPROBE_DEFER)
+			if (ret == -EPROBE_DEFER) {
+				of_node_put(iphynode);
+				of_node_put(mdio_internal);
 				return ret;
+			}
 			continue;
 		}
 		dev_info(priv->device, "Found internal PHY node\n");
+		of_node_put(iphynode);
+		of_node_put(mdio_internal);
 		return 0;
 	}
+
+	of_node_put(mdio_internal);
 	return -ENODEV;
 }
 
-- 
2.17.1