Re: [PATCH net-next v2] net: airoha: Validate egress gdm port in airoha_ppe_foe_entry_prepare()

[Paolo Abeni <pabeni@redhat.com>]

On 3/15/25 3:59 PM, Lorenzo Bianconi wrote:
>>> Fix the issue validating egress gdm port in airoha_ppe_foe_entry_prepare
>>> routine.
>>
>> A more interesting question is, why do you see an invalid port? Is the
>> hardware broken? Something not correctly configured? Are you just
>> papering over the crack?
>>
>>> -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);
>>
>> If port is invalid, is dev also invalid? And if dev is invalid, could
>> dereferencing it to get priv cause an opps?
> 
> I do not think this is a hw problem. Running bidirectional high load traffic,
> I got the sporadic crash reported above. In particular, netfilter runs
> airoha_ppe_flow_offload_replace() providing the egress net_device pointer used
> in airoha_ppe_foe_entry_prepare(). Debugging with gdb, I discovered the system
> crashes dereferencing port pointer in airoha_ppe_foe_entry_prepare() (even if
> dev pointer is not NULL). Adding this sanity check makes the system stable.
> Please note a similar check is available even in mtk driver [0].

I agree with Andrew, you need a better understanding of the root cause.
This really looks like papering over some deeper issue.

AFAICS 'dev' is fetched from the airoha driver itself a few lines
before. Possibly you should double check that code.

Thanks,

Paolo