Re: [PATCH net v2] ipv6: seg6: clear IPv4 control block in End.DT4

[Nicolas Dichtel]

Le 04/08/2026 à 11:46, David Lee a écrit :
> From: Kyle Zeng <kylebot@xxxxxxxxxx>
> 
> 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 <kylebot@xxxxxxxxxx>
> Co-developed-by: David Lee <david.lee@xxxxxxxxxxxxxxx>
> Signed-off-by: David Lee <david.lee@xxxxxxxxxxxxxxx>
> ---
> 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?