ext4: fix potential integer overflow

ext4: fix potential integer overflow

Orabug: 23330858

[ Upstream commit 46901760b46064964b41015d00c140c83aa05bcf ]

Since sizeof(ext_new_group_data) > sizeof(ext_new_flex_group_data),
integer overflow could be happened.
Therefore, need to fix integer overflow sanitization.

Cc: stable@vger.kernel.org
Signed-off-by: Insu Yun <wuninsu@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
(cherry picked from commit 9d7679794e9cd701890d997a76024b2239f90638)

Signed-off-by: Dan Duval <dan.duval@oracle.com>