CVE-2022-49080 mm/mempolicy: fix mpol_new leak in shared_policy_replace

In the Linux kernel, the following vulnerability has been resolved: mm/mempolicy: fix mpolnew leak in sharedpolicyreplace If mpolnew is allocated but not used in restart loop, mpolnew will be freed via mpolput before returning to the caller. But refcnt is not initialized yet, so mpolput could not...