Re: [PATCH v2 net 2/2] ipv4: reserve one IP ID per segment for UDP GSO packets
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From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: 2026-09-30 15:12:34
Eric Dumazet wrote:
__ip_make_skb() reserves a single IP ID for UDP GSO packets, but GSO
assigns one IP ID per segment. Following packets then reuse these IDs,
either from inet->inet_id or from the shared generator.
Unless IP_PMTUDISC_DO/PROBE is used, DF is not set on UDP GSO packets,
so segments can be fragmented on the path and IP ID reuse can lead to
incorrect reassembly.
Reserve one IP ID per segment, using the same test as udp_send_skb().
Fixes: bec1f6f69736 ("udp: generate gso with UDP_SEGMENT")
Signed-off-by: Eric Dumazet <edumazet@kernel.org>
Reviewed-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Cc: Willem de Bruijn <willemb@google.com>Reviewed-by: Willem de Bruijn <willemb@google.com>