[SCSI] stex: fix scan of nonexistent lun

During a manual scan, a user can send command to a nonexistent
lun, precisely at the point of max_lun. Normally it's possible
(but not required) that the firmware has the knowledge that it
is an invalid lun. In the particular case when max_lun is 256,
however, the nonexistent lun 256 will be confused with lun 0,
because the lun member in a request message is only u8, and 256
will become 0. So we need to fix the problem, at least, at the
driver level.
Signed-off-by: Ed Lin <ed.lin@promise.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

drivers/scsi/stex.c

@@ -623,6 +623,11 @@ stex_queuecommand(struct scsi_cmnd *cmd, void (* done)(struct scsi_cmnd *))
 		}
 		break;
 	case INQUIRY:
+		if (lun >= host->max_lun) {
+			cmd->result = DID_NO_CONNECT << 16;
+			done(cmd);
+			return 0;
+		}
 		if (id != host->max_id - 1)
 			break;
 		if (!lun && !cmd->device->channel &&