Re: [PATCH net v2] vlan: skip nested type that is not IFLA_VLAN_QOS_MAPPING

[Simon Horman]

On Thu, Jan 18, 2024 at 09:03:06PM +0800, Lin Ma wrote:
> In the vlan_changelink function, a loop is used to parse the nested
> attributes IFLA_VLAN_EGRESS_QOS and IFLA_VLAN_INGRESS_QOS in order to
> obtain the struct ifla_vlan_qos_mapping. These two nested attributes are
> checked in the vlan_validate_qos_map function, which calls
> nla_validate_nested_deprecated with the vlan_map_policy.
> 
> However, this deprecated validator applies a LIBERAL strictness, allowing
> the presence of an attribute with the type IFLA_VLAN_QOS_UNSPEC.
> Consequently, the loop in vlan_changelink may parse an attribute of type
> IFLA_VLAN_QOS_UNSPEC and believe it carries a payload of
> struct ifla_vlan_qos_mapping, which is not necessarily true.
> 
> To address this issue and ensure compatibility, this patch introduces two
> type checks that skip attributes whose type is not IFLA_VLAN_QOS_MAPPING.
> 
> Fixes: 07b5b17e157b ("[VLAN]: Use rtnl_link API")
> Signed-off-by: Lin Ma <linma@xxxxxxxxxx>
> ---
> V1 -> V2: make net-next to net as suggested by Paolo
>           and add Fixes tag for this one

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>