UBUNTU-CVE-2026-98229: High severity ubuntu/linux-aws vulnerability

In the Linux kernel, the following vulnerability has been resolved: xfrm: save input state data before secpath resets xfrminput() stores the current xfrmstate in the skb secpath while it continues receive-side processing. Some input paths can reset that secpath before xfrminput() has finished dereferencing the state. Receive callback users such as VTI and XFRM interfaces can reset the secpath. The VTI receive path does so before checking whether the packet crosses network namespaces, while the XFRM interface path does so only for cross-network-namespace packets. The XFRMMAXDEPTH error path can also reset the secpath before the final drop callback reports the current state's protocol. If secpathreset() drops the last state reference while the state is concurrently deleted, xfrminput() can still dereference the freed state when selecting transportfinish() or reporting the drop callback protocol. Save the state protocol on the stack while the state is still valid, and use the already saved address family for transportfinish(). A larval XFRMSTATEACQ state has no type, so retain nexthdr as its protocol. This preserves the existing drop-path fallback while avoiding the post-reset state dereferences without adding an extra state reference to every received packet.