CVE-2025-39984 net: tun: Update napi->skb after XDP process

In the Linux kernel, the following vulnerability has been resolved: net: tun: Update napi-skb after XDP process The syzbot report a UAF issue: BUG: KASAN: slab-use-after-free in skbresetmacheader include/linux/skbuff.h:3150 inline BUG: KASAN: slab-use-after-free in napifragsskb net/core/gro.c:723...