scsi: core: Make scsi_internal_device_unblock_nowait() reject invalid new_state

The only 'new_state' values passed by upstream kernel code to
scsi_internal_device_unblock_nowait() are SDEV_RUNNING and
SDEV_TRANSPORT_OFFLINE. These are the only values that should be passed to
this function. Hence check the value of the 'new_state' argument to avoid
that scsi_internal_device_unblock_nowait() would be used to trigger an
illegal SCSI device state transition. In this context 'illegal' means not
allowed by scsi_device_set_state().

Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Cc: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_lib.c

@@ -2707,6 +2707,14 @@ void scsi_start_queue(struct scsi_device *sdev)
 int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
 					enum scsi_device_state new_state)
 {
+	switch (new_state) {
+	case SDEV_RUNNING:
+	case SDEV_TRANSPORT_OFFLINE:
+		break;
+	default:
+		return -EINVAL;
+	}
+
 	/*
 	 * Try to transition the scsi device to SDEV_RUNNING or one of the
 	 * offlined states and goose the device queue if successful.