CVE-2026-64410

In the Linux kernel, the following vulnerability has been resolved:

netfilter: flowtable: IPIP tunnel hardware offload is not yet support

No driver supports for IPIP tunnels yet, give up early on setting up the

hardware offload for this scenario.

This patch adds a stub that can be enhanced to add more configuration

that are currently not supported. As of now, the offload work is

enqueued to the worker, then ignored if the hardware offload

configuration is not supported.

Check the NFFLOWHW flag to know if this entry was already tried once

to be offloaded so this is not retried on refresh when unsupported. Move

NFFLOWHW flag check to nfflowoffloadadd(). If this NFFLOW_HW flag

is unset the del and stats variants are never called.

This can be updated later on to skip hardware offload work to be queued

in case hardware offload does not support it.