userfaultfd: fix a race between writeprotect and exit_mmap()
This is an automated ID intended to aid in discovery of potential security vulnerabilities. The actual impact and attack plausibility have not yet been proven. This ID is fixed in Linux Kernel version v5.14.15 by commit 149958ecd0627a9f1e9c678c25c665400054cd6a, it was introduced in version v5.7 by commit 63b2d4174c4ad1f40b48d7138e71bcb564c1fe03. For more details please see the references link.