CVE-2024-26641 ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()

In the Linux kernel, the following vulnerability has been resolved: ip6tunnel: make sure to pull inner header in ip6tnlrcv syzbot found ip6tnlrcv could access unitiliazed data 1. Call pskbinetmaypull to fix this, and initialize ipv6h variable after this call as it can change skb-head. 1 BUG: KMSA...