Re: [PATCH nf] netfilter: br_netfilter: restore VLAN tag on refragmented IPv6 packets

[Andrea Parri <parri.andrea@gmail.com>]

[ Resending with the full Cc list, which I dropped by mistake in my
  previous reply. ]

On Mon, Sep 28, 2026 at 04:19:47PM +0000, netdev-bot+sinfo@kernel.org wrote:
> This is an automated message. This series looks like a fix, but its
> commit messages seem to be missing some information:
>
>  - Whether the issue was actually triggered, or is only theoretical
>    (e.g. found by code inspection). If it was triggered please include
>    the symptoms, like the stack trace or error messages.

The issue was triggered, not only found by code inspection. I
reproduced it under virt-ng with a local test on a VLAN-aware bridge
with br_netfilter and IPv6 conntrack defrag enabled. The test sends a
fragmented IPv4 packet on one VLAN, then a fragmented IPv6 packet on
another VLAN that the bridge floods to several ports. The test is
available on request.

Symptoms: with the patch not applied, the refragmented IPv6 packets
leave the bridge with the wrong VLAN tag. This is the tag of the earlier
IPv4 flow when both refragmentations run on the same CPU. Otherwise the
packets go out untagged. There is no crash or warning; the only effect
is the wrong or missing tag on the wire. With the patch applied, all the
IPv6 fragments keep the correct VLAN tag.

Thanks,
  Andrea