Re: [PATCH net-next v4 4/4] net: gro: move L3 flush checks to tcp_gro_receive

[Richard Gobert]

Eric Dumazet wrote:
> On Mon, Mar 25, 2024 at 7:27 PM Richard Gobert <richardbgobert@xxxxxxxxx> wrote:
>>
>> {inet,ipv6}_gro_receive functions perform flush checks (ttl, flags,
>> iph->id, ...) against all packets in a loop. These flush checks are used
>> currently only in tcp flows in GRO.
> 
> I think this is a bug.
> 
> GRO should not aggregate packets if their ttl/tos fields do not match.

AFAIU, the only UDP flow where ttl/flush_id need to be checked is when
udp_gro_receive_segment calls skb_gro_receive - could you confirm / point
out if there are any other flows to which these flush checks may be
relevant?

As I've discussed with Willem in v3 I prefer to fix this bug in a separate
series.