net: dsa: mt7530: fix null pointer dereferencing in port5 setup

The 2nd gmac of mediatek soc ethernet may not be connected to a PHY
and a phy-handle isn't always available.
Unfortunately, mt7530 dsa driver assumes that the 2nd gmac is always
connected to switch port 5 and setup mt7530 according to phy address
of 2nd gmac node, causing null pointer dereferencing when phy-handle
isn't defined in dts.
This commit fix this setup code by checking return value of
of_parse_phandle before using it.

Fixes: 38f790a80560 ("net: dsa: mt7530: Add support for port 5")
Signed-off-by: Chuanhong Guo <gch981213@gmail.com>
Reviewed-by: Vivien Didelot <vivien.didelot@gmail.com>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: René van Dorst <opensource@vdorst.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index ef57552..2d0d91d 100644 (file)
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -1403,6 +1403,9 @@ mt7530_setup(struct dsa_switch *ds)
                                continue;
 
                        phy_node = of_parse_phandle(mac_np, "phy-handle", 0);
+                       if (!phy_node)
+                               continue;
+
                        if (phy_node->parent == priv->dev->of_node->parent) {
                                ret = of_get_phy_mode(mac_np, &interface);
                                if (ret && ret != -ENODEV)