[PATCH net v3] net: airoha: Validate egress gdm port in airoha_ppe_foe_entry_prepare()

[Lorenzo Bianconi]

Device pointer in airoha_ppe_foe_entry_prepare routine is not strictly
necessary 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: 00a7678310fe ("net: airoha: Introduce flowtable offload support")
Signed-off-by: Lorenzo Bianconi <lorenzo at kernel.org>
---
Changes in v3:
- Rebase on top of net tree
- Fix commit log
- Link to v2: https://lore.kernel.org/r/20250315-airoha-flowtable-null-ptr-fix-v2-1-94b923d30234@kernel.org

Changes in v2:
- Avoid checking netdev_priv pointer since it is always not NULL
- Link to v1: https://lore.kernel.org/r/20250312-airoha-flowtable-null-ptr-fix-v1-1-6363fab884d0@kernel.org
---
 drivers/net/ethernet/airoha/airoha_eth.c | 13 +++++++++++++
 drivers/net/ethernet/airoha/airoha_eth.h |  3 +++
 drivers/net/ethernet/airoha/airoha_ppe.c | 10 ++++++++--
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index c0a642568ac115ea9df6fbaf7133627a4405a36c..bf9c882e9c8b087dbf5e907636547a0117d1b96a 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -2454,6 +2454,19 @@ static void airoha_metadata_dst_free(struct airoha_gdm_port *port)
 	}
 }
 
+int 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 0;
+	}
+
+	return -EINVAL;
+}
+
 static int airoha_alloc_gdm_port(struct airoha_eth *eth,
 				 struct device_node *np, int index)
 {
diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
index 60690b685710c72a2e15c6c6c94240108dafa1c1..d199b8adffc0b25c369dc19cdc074c50af40e3bf 100644
--- a/drivers/net/ethernet/airoha/airoha_eth.h
+++ b/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)
 
+int 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);
diff --git a/drivers/net/ethernet/airoha/airoha_ppe.c b/drivers/net/ethernet/airoha/airoha_ppe.c
index 8b55e871352d359fa692c253d3f3315c619472b3..65833e2058194a64569eafec08b80df8190bba6c 100644
--- a/drivers/net/ethernet/airoha/airoha_ppe.c
+++ b/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)
@@ -224,6 +225,11 @@ static int airoha_ppe_foe_entry_prepare(struct airoha_foe_entry *hwe,
 	if (dev) {
 		struct airoha_gdm_port *port = netdev_priv(dev);
 		u8 pse_port;
+		int err;
+
+		err = airoha_is_valid_gdm_port(eth, port);
+		if (err)
+			return err;
 
 		if (dsa_port >= 0)
 			pse_port = port->id == 4 ? FE_PSE_PORT_GDM4 : port->id;
@@ -633,7 +639,7 @@ 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;

---
base-commit: 2ea396448f26d0d7d66224cb56500a6789c7ed07
change-id: 20250331-airoha-validate-egress-gdm-port-336c879960ca

Best regards,
-- 
Lorenzo Bianconi <lorenzo at kernel.org>