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[35.245.46.111]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8ac53e96182sm7395337b3.35.2026.09.30.08.12.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 30 Sep 2026 08:12:29 -0700 (PDT) Date: Wed, 30 Sep 2026 11:12:29 -0400 From: Willem de Bruijn To: Eric Dumazet , "David S . Miller" , Jakub Kicinski , Paolo Abeni Cc: Simon Horman , David Ahern , Ido Schimmel , netdev@vger.kernel.org, edumazet@google.com, Eric Dumazet , Jiayuan Chen , Willem de Bruijn Message-ID: In-Reply-To: <20260930144018.1174068-3-edumazet@kernel.org> References: <20260930144018.1174068-1-edumazet@kernel.org> <20260930144018.1174068-3-edumazet@kernel.org> Subject: Re: [PATCH v2 net 2/2] ipv4: reserve one IP ID per segment for UDP GSO packets Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit 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 > Reviewed-by: Jiayuan Chen > Cc: Willem de Bruijn Reviewed-by: Willem de Bruijn