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From:   Alex Dewar <alex.dewar90@gmail.com>
To:     Landen Chao <landen.chao@mediatek.com>
Cc:     Alex Dewar <alex.dewar90@gmail.com>,
        Sean Wang <sean.wang@mediatek.com>,
        Andrew Lunn <andrew@lunn.ch>,
        Vivien Didelot <vivien.didelot@gmail.com>,
        Florian Fainelli <f.fainelli@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Jakub Kicinski <kuba@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Russell King <linux@armlinux.org.uk>, netdev@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: [PATCH v3] net: dsa: mt7530: Add some return-value checks
Date:   Thu, 24 Sep 2020 15:05:35 +0100
Message-Id: <20200924140535.5940-1-alex.dewar90@gmail.com>
In-Reply-To: <1600953934.19244.2.camel@mtksdccf07>
References: <1600953934.19244.2.camel@mtksdccf07>
MIME-Version: 1.0
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In mt7531_cpu_port_config(), if the variable port is neither 5 nor 6,
then variable interface will be used uninitialised. Change the function
to return -EINVAL in this case.

As the return value of mt7531_cpu_port_config() is never checked
(even though it returns an int) add a check in the correct place so that
the error can be passed up the call stack. Now that we correctly handle
errors thrown in this function, also check the return value of
mt7531_mac_config() in case an error occurs here. Also add misisng
checks to mt7530_setup() and mt7531_setup(), which are another level
further up the call stack.

Fixes: c288575f7810 ("net: dsa: mt7530: Add the support of MT7531 switch")
Addresses-Coverity: 1496993 ("Uninitialized variables")
Signed-off-by: Alex Dewar <alex.dewar90@gmail.com>
---

Hi Landen,

Here you go!

v3:
	- fix checkpatch warning about braces (Landen)
v2:
	- fix typo in commit message
	- split variable declarations onto multiple lines (Gustavo)
	- add additional checks for mt753*_setup (Landen)

 drivers/net/dsa/mt7530.c | 33 ++++++++++++++++++++++++---------
 1 file changed, 24 insertions(+), 9 deletions(-)

diff --git a/drivers/net/dsa/mt7530.c b/drivers/net/dsa/mt7530.c
index 61388945d316..23b2386318b2 100644
--- a/drivers/net/dsa/mt7530.c
+++ b/drivers/net/dsa/mt7530.c
@@ -945,10 +945,14 @@ static int
 mt753x_cpu_port_enable(struct dsa_switch *ds, int port)
 {
 	struct mt7530_priv *priv = ds->priv;
+	int ret;
 
 	/* Setup max capability of CPU port at first */
-	if (priv->info->cpu_port_config)
-		priv->info->cpu_port_config(ds, port);
+	if (priv->info->cpu_port_config) {
+		ret = priv->info->cpu_port_config(ds, port);
+		if (ret)
+			return ret;
+	}
 
 	/* Enable Mediatek header mode on the cpu port */
 	mt7530_write(priv, MT7530_PVC_P(port),
@@ -1631,10 +1635,13 @@ mt7530_setup(struct dsa_switch *ds)
 		mt7530_rmw(priv, MT7530_PCR_P(i), PCR_MATRIX_MASK,
 			   PCR_MATRIX_CLR);
 
-		if (dsa_is_cpu_port(ds, i))
-			mt753x_cpu_port_enable(ds, i);
-		else
+		if (dsa_is_cpu_port(ds, i)) {
+			ret = mt753x_cpu_port_enable(ds, i);
+			if (ret)
+				return ret;
+		} else {
 			mt7530_port_disable(ds, i);
+		}
 
 		/* Enable consistent egress tag */
 		mt7530_rmw(priv, MT7530_PVC_P(i), PVC_EG_TAG_MASK,
@@ -1785,10 +1792,13 @@ mt7531_setup(struct dsa_switch *ds)
 
 		mt7530_set(priv, MT7531_DBG_CNT(i), MT7531_DIS_CLR);
 
-		if (dsa_is_cpu_port(ds, i))
-			mt753x_cpu_port_enable(ds, i);
-		else
+		if (dsa_is_cpu_port(ds, i)) {
+			ret = mt753x_cpu_port_enable(ds, i);
+			if (ret)
+				return ret;
+		} else {
 			mt7530_port_disable(ds, i);
+		}
 
 		/* Enable consistent egress tag */
 		mt7530_rmw(priv, MT7530_PVC_P(i), PVC_EG_TAG_MASK,
@@ -2276,6 +2286,7 @@ mt7531_cpu_port_config(struct dsa_switch *ds, int port)
 	struct mt7530_priv *priv = ds->priv;
 	phy_interface_t interface;
 	int speed;
+	int ret;
 
 	switch (port) {
 	case 5:
@@ -2293,6 +2304,8 @@ mt7531_cpu_port_config(struct dsa_switch *ds, int port)
 
 		priv->p6_interface = interface;
 		break;
+	default:
+		return -EINVAL;
 	}
 
 	if (interface == PHY_INTERFACE_MODE_2500BASEX)
@@ -2300,7 +2313,9 @@ mt7531_cpu_port_config(struct dsa_switch *ds, int port)
 	else
 		speed = SPEED_1000;
 
-	mt7531_mac_config(ds, port, MLO_AN_FIXED, interface);
+	ret = mt7531_mac_config(ds, port, MLO_AN_FIXED, interface);
+	if (ret)
+		return ret;
 	mt7530_write(priv, MT7530_PMCR_P(port),
 		     PMCR_CPU_PORT_SETTING(priv->id));
 	mt753x_phylink_mac_link_up(ds, port, MLO_AN_FIXED, interface, NULL,
-- 
2.28.0