ocfs2: add extra consistency check to ocfs2_dx_dir_lookup_rec()

ocfs2: add extra consistency check to ocfs2_dx_dir_lookup_rec()

In 'ocfs2_dx_dir_lookup_rec()', check whether an extent list length of the
directory indexing block matches the one configured via the superblock
parameters established at mount, thus preventing an out-of-bounds accesses
while iterating over the extent records below.

Link: https://lkml.kernel.org/r/20251007094626.196143-1-dmantipov@yandex.ru
Reported-by: syzbot+30b53487d00b4f7f0922@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=30b53487d00b4f7f0922
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Reviewed-by: Joseph Qi <joseph.qi@linux.alibaba.com>
Reviewed-by: Heming Zhao <heming.zhao@suse.com>>
Cc: Mark Fasheh <mark@fasheh.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Cc: Changwei Ge <gechangwei@live.cn>
Cc: Jun Piao <piaojun@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>