CVE-2024-39500 sock_map: avoid race between sock_map_close and sk_psock_put

In the Linux kernel, the following vulnerability has been resolved: sockmap: avoid race between sockmapclose and skpsockput skpsockget will return NULL if the refcount of psock has gone to 0, which will happen when the last call of skpsockput is done. However, skpsockdrop may not have finished ye...