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

[Simon Horman]

On Mon, Mar 31, 2025 at 12:14:09PM +0200, Lorenzo Bianconi wrote:
> 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

nit: I think it would be clearer if "necessary" was dropped from the line
     above.

> 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)

nit: given the name of the function, perhaps returning a bool is more
     appropriate.

> +{
> +	int i;
> +
> +	for (i = 0; i < ARRAY_SIZE(eth->ports); i++) {
> +		if (eth->ports[i] == port)
> +			return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +

...