Re: [PATCH net v2] seg6: fix transport header for inner IPv4 with IP options

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@xxxxxxxxxx>:

On Wed, 28 Oct 2026 18:15:11 +0100 you wrote:
> The End.DT4, End.DT46 (its IPv4 path only) and End.DX4 behaviors set the
> transport header of the decapsulated IPv4 packet at a fixed 20 bytes, the
> size of an IPv4 header without options. They do not validate the header
> length either. With options, the transport header points at the first
> option byte. The effects include:
> - ping -R sends an echo request with a 60-byte IPv4 header to a local
>   address through an End.DT4 or an End.DX4 SID. Since icmp_rcv()
>   computes the ICMP checksum from the first option byte, the request
>   fails the check and is counted in IcmpInCsumErrors.
> - A UDP datagram can reach a port that an iptables rule drops. The rule
>   checks the UDP header after the full IPv4 header, while the socket
>   lookup reads it at the fixed 20-byte offset.
> - With an inbound AH state, ah_input() reads the AH header at the fixed
>   20-byte offset, but copies the IPv4 header over it with the length in
>   the IHL field. A packet shorter than that length can make ah_input()
>   write past the end of the data, into skb_shared_info when the skb has
>   no tailroom.
> 
> [...]

Here is the summary with links:
  - [net,v2] seg6: fix transport header for inner IPv4 with IP options
    https://git.kernel.org/netdev/net/c/5838f10563d5

You are awesome, thank you!
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