[PATCH 4.18 284/350] net: bcmgenet: fix OF child-node lookup

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <johan@xxxxxxxxxx>

commit d397dbe606120a1ea1b11b0020c3f7a3852da5ac upstream.

Use the new of_get_compatible_child() helper to lookup the mdio 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 node of the device being probed).

Fixes: aa09677cba42 ("net: bcmgenet: add MDIO routines")
Cc: stable <stable@xxxxxxxxxxxxxxx>     # 3.15
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Signed-off-by: Rob Herring <robh@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/net/ethernet/broadcom/genet/bcmmii.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/broadcom/genet/bcmmii.c
+++ b/drivers/net/ethernet/broadcom/genet/bcmmii.c
@@ -342,7 +342,7 @@ static struct device_node *bcmgenet_mii_
 	if (!compat)
 		return NULL;
 
-	priv->mdio_dn = of_find_compatible_node(dn, NULL, compat);
+	priv->mdio_dn = of_get_compatible_child(dn, compat);
 	kfree(compat);
 	if (!priv->mdio_dn) {
 		dev_err(kdev, "unable to find MDIO bus node\n");