net: airoha: Delay offloading until all net_devices are fully registered

Netfilter flowtable can theoretically try to offload flower rules as soon
as a net_device is registered while all the other ones are not
registered or initialized, triggering a possible NULL pointer dereferencing
of qdma pointer in airoha_ppe_set_cpu_port routine. Moreover, if
register_netdev() fails for a particular net_device, there is a small
race if Netfilter tries to offload flowtable rules before all the
net_devices are properly unregistered in airoha_probe() error patch,
triggering a NULL pointer dereferencing in airoha_ppe_set_cpu_port
routine. In order to avoid any possible race, delay offloading until
all net_devices are registered in the networking subsystem.

Signed-off-by: Lorenzo Bianconi <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Jakub Kicinski <[email protected]>

Author: LorenzoBianconi

drivers/net/ethernet/airoha/airoha_eth.c

@@ -2962,6 +2962,8 @@ static int airoha_register_gdm_devices(struct airoha_eth *eth)
 			return err;
 	}
 
+	set_bit(DEV_STATE_REGISTERED, &eth->state);
+
 	return 0;
 }
 

drivers/net/ethernet/airoha/airoha_eth.h

@@ -88,6 +88,7 @@ enum {
 
 enum {
 	DEV_STATE_INITIALIZED,
+	DEV_STATE_REGISTERED,
 };
 
 enum {

drivers/net/ethernet/airoha/airoha_ppe.c

@@ -1368,6 +1368,13 @@ int airoha_ppe_setup_tc_block_cb(struct airoha_ppe_dev *dev, void *type_data)
 	struct airoha_eth *eth = ppe->eth;
 	int err = 0;
 
+	/* Netfilter flowtable can try to offload flower rules while not all
+	 * the net_devices are registered or initialized. Delay offloading
+	 * until all net_devices are registered in the system.
+	 */
+	if (!test_bit(DEV_STATE_REGISTERED, &eth->state))
+		return -EBUSY;
+
 	mutex_lock(&flow_offload_mutex);
 
 	if (!eth->npu)