ipack: ipoctal: fix stack information leak

ipack: ipoctal: fix stack information leak

commit a89936cce87d60766a75732a9e7e25c51164f47c upstream.

The tty driver name is used also after registering the driver and must
specifically not be allocated on the stack to avoid leaking information
to user space (or triggering an oops).

Drivers should not try to encode topology information in the tty device
name but this one snuck in through staging without anyone noticing and
another driver has since copied this malpractice.

Fixing the ABI is a separate issue, but this at least plugs the security
hole.

Fixes: ad409ec391d7 ("Staging: ipack: add support for IP-OCTAL mezzanine board")
Cc: stable@vger.kernel.org      # 3.5
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917114622.5412-2-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>