If the device is disconnected while serial_open() is executing and
either try_module_get() or the device specific open function fails, the
kref_put() call in the 'bailout_kref_put' label will free the memory
pointed out by 'port'.

The subsequent dereferences in the 'bailout_kref_put' label will be
invalid.

The fix is just to assure kref_put() is called after any 'port' usage.
Signed-off-by: Luiz Fernando N. Capitulino <lcapitulino@mandriva.com.br>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>