netdev - [PATCH RFC net-next 09/13] net: dsa: mroute: don't panic the kernel if called without the prepare phase

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Date:   Fri, 22 May 2020 00:10:32 +0300
From:   Vladimir Oltean <olteanv@...il.com>
To:     andrew@...n.ch, f.fainelli@...il.com, vivien.didelot@...il.com,
        davem@...emloft.net
Cc:     jiri@...nulli.us, idosch@...sch.org, kuba@...nel.org,
        ivecera@...hat.com, netdev@...r.kernel.org,
        horatiu.vultur@...rochip.com, allan.nielsen@...rochip.com,
        nikolay@...ulusnetworks.com, roopa@...ulusnetworks.com
Subject: [PATCH RFC net-next 09/13] net: dsa: mroute: don't panic the kernel if called without the prepare phase

From: Vladimir Oltean <vladimir.oltean@....com>

Currently, this function would check the port_egress_floods pointer only
in the preparation phase, the assumption being that the caller wouldn't
proceed to a second call since it returned -EOPNOTSUPP. If the function
were to be called a second time though, the port_egress_floods pointer
would not be checked and the driver would proceed to dereference it.

Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
 net/dsa/port.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/dsa/port.c b/net/dsa/port.c
index e23ece229c7e..c4032f79225a 100644
--- a/net/dsa/port.c
+++ b/net/dsa/port.c
@@ -324,8 +324,11 @@ int dsa_port_mrouter(struct dsa_port *dp, bool mrouter,
 	struct dsa_switch *ds = dp->ds;
 	int port = dp->index;
 
+	if (!ds->ops->port_egress_floods)
+		return -EOPNOTSUPP;
+
 	if (switchdev_trans_ph_prepare(trans))
-		return ds->ops->port_egress_floods ? 0 : -EOPNOTSUPP;
+		return 0;
 
 	return ds->ops->port_egress_floods(ds, port, true, mrouter);
 }
-- 
2.25.1