net: mscc: ocelot: Fix crash when adding interface under a lag

Commit 15faa1f67ab4 ("lan966x: Fix crash when adding interface under a lag")
fixed a similar issue in the lan966x driver caused by a NULL pointer dereference.
The ocelot_set_aggr_pgids() function in the ocelot driver has similar logic
and is susceptible to the same crash.

This issue specifically affects the ocelot_vsc7514.c frontend, which leaves
unused ports as NULL pointers. The felix_vsc9959.c frontend is unaffected as
it uses the DSA framework which registers all ports.

Fix this by checking if the port pointer is valid before accessing it.

Fixes: 528d3f190c98 ("net: mscc: ocelot: drop the use of the "lags" array")
Signed-off-by: Jerry Wu <w.7erry@foxmail.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Link: https://patch.msgid.link/tencent_75EF812B305E26B0869C673DD1160866C90A@qq.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index 08bee56aea35f311979742a17b519df5be27533a..c345d9b17c8921b335e1bbbd7e2cc1add450794a 100644 (file)
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -2307,14 +2307,16 @@ static void ocelot_set_aggr_pgids(struct ocelot *ocelot)
 
        /* Now, set PGIDs for each active LAG */
        for (lag = 0; lag < ocelot->num_phys_ports; lag++) {
-               struct net_device *bond = ocelot->ports[lag]->bond;
+               struct ocelot_port *ocelot_port = ocelot->ports[lag];
                int num_active_ports = 0;
+               struct net_device *bond;
                unsigned long bond_mask;
                u8 aggr_idx[16];
 
-               if (!bond || (visited & BIT(lag)))
+               if (!ocelot_port || !ocelot_port->bond || (visited & BIT(lag)))
                        continue;
 
+               bond = ocelot_port->bond;
                bond_mask = ocelot_get_bond_mask(ocelot, bond);
 
                for_each_set_bit(port, &bond_mask, ocelot->num_phys_ports) {