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Mon, 08 Jun 2026 06:08:36 -0700 (PDT) Received: from localhost ([104.28.193.185]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-490c2d37edbsm300135675e9.2.2026.06.08.06.08.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 08 Jun 2026 06:08:35 -0700 (PDT) From: Mariusz Klimek To: netdev@vger.kernel.org Cc: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, dsahern@kernel.org, idosch@nvidia.com, ncardwell@google.com, shuah@kernel.org, kuniyu@google.com, alice@isovalent.com, Mariusz Klimek Subject: [PATCH net-next 01/10] ipv6: do not fragment packets into jumbograms Date: Mon, 8 Jun 2026 15:07:46 +0200 Message-ID: <20260608130755.5626-2-maklimek97@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260608130755.5626-1-maklimek97@gmail.com> References: <20260608130755.5626-1-maklimek97@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit This patch prevents packets from being fragmented into jumbograms by capping the effective MTU to IP6_MAX_MTU in ip6_fragment, as RFC2675 prohibits a Jumbo Payload option from being carried in a packet that carries a fragment header. Signed-off-by: Mariusz Klimek --- net/ipv6/ip6_output.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c index c14adcdd4396..67c34fb281c6 100644 --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -935,6 +935,8 @@ int ip6_fragment(struct net *net, struct sock *sk, struct sk_buff *skb, } if (mtu < hlen + sizeof(struct frag_hdr) + 8) goto fail_toobig; + else if (unlikely(mtu > IP6_MAX_MTU)) + mtu = IP6_MAX_MTU; mtu -= hlen + sizeof(struct frag_hdr); frag_id = ipv6_select_ident(net, &ipv6_hdr(skb)->daddr, -- 2.47.3