linux-kernel - [PATCH 5.5 05/44] net: dsa: mt7530: fix null pointer dereferencing in port5 setup

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Date:   Sat, 11 Apr 2020 14:09:25 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Chuanhong Guo <gch981213@...il.com>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        René van Dorst <opensource@...rst.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 5.5 05/44] net: dsa: mt7530: fix null pointer dereferencing in port5 setup

From: Chuanhong Guo <gch981213@...il.com>

[ Upstream commit 0452800f6db4ed0a42ffb15867c0acfd68829f6a ]

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@...il.com>
Reviewed-by: Vivien Didelot <vivien.didelot@...il.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Tested-by: René van Dorst <opensource@...rst.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/dsa/mt7530.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -1355,6 +1355,9 @@ 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)