The commit ab2e53c8a (grub-mkconfig: Honor a symlink when generating
configuration by grub-mkconfig) has inadvertently discarded umask for
creating grub.cfg in the process of running grub-mkconfig. The resulting
wrong permission (0644) would allow unprivileged users to read GRUB
configuration file content. This presents a low confidentiality risk
as grub.cfg may contain non-secured plain-text passwords.
This patch restores the missing umask and sets the creation file mode
to 0600 preventing unprivileged access.
Fixes: CVE-2021-3981
Signed-off-by: Michael Chang <mchang@suse.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>