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

pfcp: fix socket lifetime on netdevice registration failure

pfcp_newlink() creates the UDP socket before register_netdevice().
If registration fails after pfcp_dev_init() succeeds, the core calls
pfcp_dev_uninit(), which releases the socket and clears pfcp->sk.
The newlink error path then releases it again, causing a NULL pointer
dereference. This was observed with failslab fault injection:

  FAULT_INJECTION: forcing a failure.
  kobject: kobject_add_internal failed for pfcp0 (error: -12 parent: net)
  BUG: KASAN: null-ptr-deref in udp_tunnel_sock_release+0x1c/0x50
  Read of size 8 at addr 0000000000000120 by task ip/1037
  Call trace:
   show_stack+0x18/0x24 (C)
   dump_stack_lvl+0x78/0x90
   print_report+0x468/0x5cc
   kasan_report+0xa4/0xf0
   __asan_load8+0x7c/0xd0
   udp_tunnel_sock_release+0x1c/0x50
   pfcp_newlink+0x128/0x184
   rtnl_newlink+0x848/0xe44
   rtnetlink_rcv_msg+0x468/0x514
   netlink_rcv_skb+0xc0/0x1f0
   rtnetlink_rcv+0x18/0x24
   netlink_unicast+0x4b8/0x558
   netlink_sendmsg+0x2b8/0x584
   ...

Return from pfcp_del_sock() if pfcp->sk is NULL.