Design/Logic Flaw

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

net: nfc: fix races in nfc_llcp_sock_get() and nfc_llcp_sock_get_sn()

Sili Luo reported a race in nfc_llcp_sock_get(), leading to UAF.

Getting a reference on the socket found in a lookup while
holding a lock should happen before releasing the lock.

nfc_llcp_sock_get_sn() has a similar problem.

Finally nfc_llcp_recv_snl() needs to make sure the socket
found by nfc_llcp_sock_from_sn() does not disappear.