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([2a01:e0a:ab7:2110:6a1d:efff:fe52:1959]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fec232d7fsm198422f8f.20.2026.08.04.07.50.02 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 04 Aug 2026 07:50:03 -0700 (PDT) Message-ID: <519a06fd-c9aa-425b-a374-607aff0a9140@6wind.com> Date: Tue, 4 Aug 2026 16:50:02 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: nicolas.dichtel@6wind.com Subject: Re: [PATCH net v2] ipv6: seg6: clear IPv4 control block in End.DT4 To: David Lee , andrea.mayer@uniroma2.it, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: Kyle Zeng , Dominik 'Disconnect3d' Czarnota , horms@kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: <20260804094625.715305-1-david.lee@trailofbits.com> From: Nicolas Dichtel Content-Language: en-US Organization: 6WIND In-Reply-To: <20260804094625.715305-1-david.lee@trailofbits.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Le 04/08/2026 à 11:46, David Lee a écrit : > From: Kyle Zeng > > The End.DT4 input path decapsulates an IPv4 packet and sends it > directly to ip_route_input() and dst_input(). It therefore bypasses > ip_rcv_core(), which normally clears IPCB. The skb still contains > IP6CB data from the outer packet, and IPv6 extension-header offsets > overlap the IPv4 option fields. This can make __ip_options_echo() > copy beyond the allocation for saved options. > > Clear IPCB after validating the inner IPv4 header and preserve the > ingress interface as ip_rcv_core() does. This prevents outer IPv6 > metadata from being interpreted as inner IPv4 options. > > Fixes: 664d6f86868b ("seg6: add support for the SRv6 End.DT4 behavior") > Assisted-by: Codex:gpt-5.6-sol Codex:gpt-5.5-cyber > Signed-off-by: Kyle Zeng > Co-developed-by: David Lee > Signed-off-by: David Lee > --- > Changes in v2: > - Restore Kyle Zeng as the patch author and correct the sign-off chain. You didn't answer my previous question: > End.DX4 also calls ip_route_input(). I guess the same problem exists. Am I > wrong?