epoll: do not insert into poll queues until all sanity checks are done

epoll: do not insert into poll queues until all sanity checks are done

commit f8d4f44df056c5b504b0d49683fb7279218fd207 upstream.

Mot-CRs-fixed: (CR)
CVE-Fixed: CVE-2021-39634
Bug: 204450605

Change-Id: If2c466f2eecd8acdb152456d94a00210a4c0af74
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Gajjala Chakradhar <gajjalac@motorola.com>
Reviewed-on: https://gerrit.mot.com/2152183
SME-Granted: SME Approvals Granted
SLTApproved: Slta Waiver
Tested-by: Jira Key
Reviewed-by: Xiangpo Zhao <zhaoxp3@motorola.com>
Submit-Approved: Jira Key