hfsplus: Fix potential buffer overflows

Commit ec81aecb ("hfs: fix a potential buffer overflow") fixed a few
potential buffer overflows in the hfs filesystem.  But as Timo Warns
pointed out, these changes also need to be made on the hfsplus
filesystem as well.

Reported-by: Timo Warns <warns@pre-sense.de>
Acked-by: WANG Cong <amwang@redhat.com>
Cc: Alexey Khoroshilov <khoroshilov@ispras.ru>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Sage Weil <sage@newdream.net>
Cc: Eugene Teo <eteo@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: stable <stable@vger.kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>