CVE-2024-40983 tipc: force a dst refcount before doing decryption

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

tipc: force a dst refcount before doing decryption

As it says in commit 3bc07321ccc2 (“xfrm: Force a dst refcount before
entering the xfrm type handlers”):

“Crypto requests might return asynchronous. In this case we leave the
rcu protected region, so force a refcount on the skb’s destination
entry before we enter the xfrm type input/output handlers.”

On TIPC decryption path it has the same problem, and skb_dst_force()
should be called before doing decryption to avoid a possible crash.

Shuang reported this issue when this warning is triggered:

[] WARNING: include/net/dst.h:337 tipc_sk_rcv+0x1055/0x1ea0 [tipc]
[] Kdump: loaded Tainted: G W --------- - - 4.18.0-496.el8.x86_64+debug
[] Workqueue: crypto cryptd_queue_worker
[] RIP: 0010:tipc_sk_rcv+0x1055/0x1ea0 [tipc]
[] Call Trace:
[] tipc_sk_mcast_rcv+0x548/0xea0 [tipc]
[] tipc_rcv+0xcf5/0x1060 [tipc]
[] tipc_aead_decrypt_done+0x215/0x2e0 [tipc]
[] cryptd_aead_crypt+0xdb/0x190
[] cryptd_queue_worker+0xed/0x190
[] process_one_work+0x93d/0x17e0