integrity: Fix possible multiple allocation in integrity_inode_get()

mainline inclusion
from mainline-v6.5-rc1
commit 9df6a487
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8C2DB
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9df6a4870dc371136e90330cfbbc51464ee66993



--------------------------------

When integrity_inode_get() is querying and inserting the cache, there
is a conditional race in the concurrent environment.

The race condition is the result of not properly implementing
"double-checked locking". In this case, it first checks to see if the
iint cache record exists before taking the lock, but doesn't check
again after taking the integrity_iint_lock.

Fixes: bf2276d1 ("ima: allocating iint improvements")
Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com>
Cc: Dmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Felix Fu <fuzhen5@huawei.com>