ima: Fix a potential NULL pointer access in ima_restore_measurement_list

mainline inclusion
from mainline-6.2-rc2
commit 11220db4
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5OBZE


CVE: NA

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

In restore_template_fmt, when kstrdup fails, a non-NULL value will still be
returned, which causes a NULL pointer access in template_desc_init_fields.

Fixes: c7d09367 ("ima: support restoring multiple template formats")
Cc: stable@kernel.org
Co-developed-by: Jiaming Li <lijiaming30@huawei.com>
Signed-off-by: Jiaming Li <lijiaming30@huawei.com>
Signed-off-by: Huaxin Lu <luhuaxin1@huawei.com>
Reviewed-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>