CVE-2026-80840 ipv6: seg6: clear IPv4 control block on IPIP decapsulation

In the Linux kernel, the following vulnerability has been resolved: ipv6: seg6: clear IPv4 control block on IPIP decapsulation End.DX4 and End.DT4 decapsulate an IPv4 packet through decapandvalidate and send it directly to IPv4 routing. The inner packet therefore bypasses iprcvcore, which normall...