net: airoha: Validate egress gdm port in airoha_ppe_foe_entry_prepare()

Dev pointer in airoha_ppe_foe_entry_prepare routine is not strictly
a device allocated by airoha_eth driver since it is an egress device
and the flowtable can contain even wlan, pppoe or vlan devices. E.g:

flowtable ft {
        hook ingress priority filter
        devices = { eth1, lan1, lan2, lan3, lan4, wlan0 }
        flags offload                               ^
                                                    |
                     "not allocated by airoha_eth" --
}

In this case airoha_get_dsa_port() will just return the original device
pointer and we can't assume netdev priv pointer points to an
airoha_gdm_port struct.
Fix the issue validating egress gdm port in airoha_ppe_foe_entry_prepare
routine before accessing net_device priv pointer.

Fixes: 00a7678 ("net: airoha: Introduce flowtable offload support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250401-airoha-validate-egress-gdm-port-v4-1-c7315d33ce10@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/airoha/airoha_eth.c

@@ -2454,6 +2454,19 @@ static void airoha_metadata_dst_free(struct airoha_gdm_port *port)
 	}
 }
 
+bool airoha_is_valid_gdm_port(struct airoha_eth *eth,
+			      struct airoha_gdm_port *port)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
+		if (eth->ports[i] == port)
+			return true;
+	}
+
+	return false;
+}
+
 static int airoha_alloc_gdm_port(struct airoha_eth *eth,
 				 struct device_node *np, int index)
 {

drivers/net/ethernet/airoha/airoha_eth.h

@@ -532,6 +532,9 @@ u32 airoha_rmw(void __iomem *base, u32 offset, u32 mask, u32 val);
 #define airoha_qdma_clear(qdma, offset, val)			\
 	airoha_rmw((qdma)->regs, (offset), (val), 0)
 
+bool airoha_is_valid_gdm_port(struct airoha_eth *eth,
+			      struct airoha_gdm_port *port);
+
 void airoha_ppe_check_skb(struct airoha_ppe *ppe, u16 hash);
 int airoha_ppe_setup_tc_block_cb(enum tc_setup_type type, void *type_data,
 				 void *cb_priv);

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -197,7 +197,8 @@ static int airoha_get_dsa_port(struct net_device **dev)
 #endif
 }
 
-static int airoha_ppe_foe_entry_prepare(struct airoha_foe_entry *hwe,
+static int airoha_ppe_foe_entry_prepare(struct airoha_eth *eth,
+					struct airoha_foe_entry *hwe,
 					struct net_device *dev, int type,
 					struct airoha_flow_data *data,
 					int l4proto)
@@ -225,6 +226,9 @@ static int airoha_ppe_foe_entry_prepare(struct airoha_foe_entry *hwe,
 		struct airoha_gdm_port *port = netdev_priv(dev);
 		u8 pse_port;
 
+		if (!airoha_is_valid_gdm_port(eth, port))
+			return -EINVAL;
+
 		if (dsa_port >= 0)
 			pse_port = port->id == 4 ? FE_PSE_PORT_GDM4 : port->id;
 		else
@@ -633,7 +637,7 @@ static int airoha_ppe_flow_offload_replace(struct airoha_gdm_port *port,
 	    !is_valid_ether_addr(data.eth.h_dest))
 		return -EINVAL;
 
-	err = airoha_ppe_foe_entry_prepare(&hwe, odev, offload_type,
+	err = airoha_ppe_foe_entry_prepare(eth, &hwe, odev, offload_type,
 					   &data, l4proto);
 	if (err)
 		return err;