isofs: Fix out of bound access for corrupted isofs image

stable inclusion
from stable-v4.19.217
commit b0ddff8d68f2e43857a84dce54c3deab181c8ae1
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9RD2M
CVE: CVE-2021-47478

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b0ddff8d68f2e43857a84dce54c3deab181c8ae1



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

commit e96a1866 upstream.

When isofs image is suitably corrupted isofs_read_inode() can read data
beyond the end of buffer. Sanity-check the directory entry length before
using it.

Reported-and-tested-by:  <syzbot+6fc7fb214625d82af7d1@syzkaller.appspotmail.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>