From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
To: Eric Dumazet <edumazet@kernel.org>,
"David S . Miller" <davem@davemloft.net>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>,
David Ahern <dsahern@kernel.org>,
Ido Schimmel <idosch@nvidia.com>,
netdev@vger.kernel.org, edumazet@google.com,
Eric Dumazet <edumazet@kernel.org>,
Jiayuan Chen <jiayuan.chen@linux.dev>,
Willem de Bruijn <willemb@google.com>
Subject: Re: [PATCH v2 net 2/2] ipv4: reserve one IP ID per segment for UDP GSO packets
Date: Wed, 30 Sep 2026 11:12:29 -0400 [thread overview]
Message-ID: <willemdebruijn.kernel.1713efd699025@gmail.com> (raw)
In-Reply-To: <20260930144018.1174068-3-edumazet@kernel.org>
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>
next prev parent reply other threads:[~2026-09-30 15:12 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-30 14:40 [PATCH v2 net 0/2] ipv4: fix IP ID reuse for GSO packets Eric Dumazet
2026-09-30 14:40 ` [PATCH v2 net 1/2] ipv4: fix IP ID reuse in ip_select_ident_segs() Eric Dumazet
2026-09-30 15:11 ` Willem de Bruijn
2026-09-30 14:40 ` [PATCH v2 net 2/2] ipv4: reserve one IP ID per segment for UDP GSO packets Eric Dumazet
2026-09-30 15:12 ` Willem de Bruijn [this message]
2026-10-05 22:10 ` [PATCH v2 net 0/2] ipv4: fix IP ID reuse for " patchwork-bot+netdevbpf
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