linux-kernel - [PATCH net] net: dsa: bcm_sf2: Fix array overrun in bcm_sf2_num_active

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Date:   Thu, 16 Sep 2021 14:33:35 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     netdev@...r.kernel.org
Cc:     Florian Fainelli <f.fainelli@...il.com>,
        Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Vladimir Oltean <olteanv@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Rafał Miłecki <rafal@...ecki.pl>,
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH net] net: dsa: bcm_sf2: Fix array overrun in bcm_sf2_num_active_ports()

After d12e1c464988 ("net: dsa: b53: Set correct number of ports in the
DSA struct") we stopped setting dsa_switch::num_ports to DSA_MAX_PORTS,
which created an off by one error between the statically allocated
bcm_sf2_priv::port_sts array (of size DSA_MAX_PORTS). When
dsa_is_cpu_port() is used, we end-up accessing an out of bounds member
and causing a NPD.

Fix this by iterating with the appropriate port count using
ds->num_ports.

Fixes: d12e1c464988 ("net: dsa: b53: Set correct number of ports in the DSA struct")
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/net/dsa/bcm_sf2.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/dsa/bcm_sf2.c b/drivers/net/dsa/bcm_sf2.c
index 6ce9ec1283e0..b6c4b3adb171 100644
--- a/drivers/net/dsa/bcm_sf2.c
+++ b/drivers/net/dsa/bcm_sf2.c
@@ -68,7 +68,7 @@ static unsigned int bcm_sf2_num_active_ports(struct dsa_switch *ds)
 	struct bcm_sf2_priv *priv = bcm_sf2_to_priv(ds);
 	unsigned int port, count = 0;
 
-	for (port = 0; port < ARRAY_SIZE(priv->port_sts); port++) {
+	for (port = 0; port < ds->num_ports; port++) {
 		if (dsa_is_cpu_port(ds, port))
 			continue;
 		if (priv->port_sts[port].enabled)
-- 
2.25.1