CVE-2026-72234: batman-adv: access unicast_ttvn skb->data only after skb realloc

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: access unicastttvn skb->data only after skb realloc

The pskbmaypull() called by batadvgetvid() could reallocate the buffer behind the skb. Variables which were pointing to the old buffer need to be reassigned to avoid an use-after-free.

This was done correctly for the ethernet header but missed for the unicastpacket pointer.