CVE-2026-72400 seg6: validate SRH length before reading fixed fields

In the Linux kernel, the following vulnerability has been resolved: seg6: validate SRH length before reading fixed fields seg6validatesrh reads fixed SRH fields such as srh-type and srh-hdrlen before checking that the supplied length covers the fixed struct ipv6srhdr fields. The BPF SEG6 encap pa...