net: stmmac: dwmac-sun8i: fix OF child-node lookup

BugLink: https://bugs.launchpad.net/bugs/1836802
[ 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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index 9eb7f65d8000d28190da780587dba562aed72152..0471e230163b994e739dec3fe02630c1fd3436c8 100644 (file)
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -654,8 +654,9 @@ 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;
@@ -669,13 +670,20 @@ 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;
 }