Re: [PATCH net v2] net: ipv6: fix TCP GSO segmentation with NAT

[Felix Fietkau]

On 10.03.25 14:50, Eric Dumazet wrote:
> On Mon, Mar 10, 2025 at 12:21 PM Felix Fietkau <nbd@xxxxxxxx> wrote:
> > When updating the source/destination address, the TCP/UDP checksum needs to
> > be updated as well.
> >
> > Fixes: bee88cd5bd83 ("net: add support for segmenting TCP fraglist GSO packets")
> > Signed-off-by: Felix Fietkau <nbd@xxxxxxxx>
> > ---
> > v2: move code to make it similar to __tcpv4_gso_segment_list_csum
> >
> >  net/ipv6/tcpv6_offload.c | 18 ++++++++++++++----
> >  1 file changed, 14 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/ipv6/tcpv6_offload.c b/net/ipv6/tcpv6_offload.c
> > index a45bf17cb2a1..34dd0cee3ba6 100644
> > --- a/net/ipv6/tcpv6_offload.c
> > +++ b/net/ipv6/tcpv6_offload.c
> > @@ -94,10 +94,20 @@ INDIRECT_CALLABLE_SCOPE int tcp6_gro_complete(struct sk_buff *skb, int thoff)
> >  }
> >
> >  static void __tcpv6_gso_segment_csum(struct sk_buff *seg,
> > +                                    struct in6_addr *oldip,
> > +                                    const struct in6_addr *newip,
> >                                      __be16 *oldport, __be16 newport)
> >  {
> >         struct tcphdr *th;
> >
> > +       if (!ipv6_addr_equal(oldip, newip)) {
> > +               inet_proto_csum_replace16(&th->check, seg,
>
> th is not initialized yet.

Sorry, I had this fixed locally, but forgot to add it before sending. 
Will send v3 later.

- Felix