target: Fix off-by-seven in target_report_luns

cdb_offset is always equal to offset - 8, so remove that one.  More
importantly, the existing code only worked correct if
se_cmd->data_length is a multiple of 8.  Pass in a length of, say, 9 and
we will happily overwrite 7 bytes of "unallocated" memory.

Now, afaics this bug is currently harmless, as allocations will
implicitly be padded to multiples of 8 bytes.  But depending on such a
fact wouldn't qualify as sound engineering practice.
Signed-off-by: NJoern Engel <joern@logfs.org>
Signed-off-by: NNicholas Bellinger <nab@linux-iscsi.org>

drivers/target/target_core_device.c

@@ -650,7 +650,7 @@ int target_report_luns(struct se_task *se_task)
 	struct se_lun *se_lun;
 	struct se_session *se_sess = se_cmd->se_sess;
 	unsigned char *buf;
-	u32 cdb_offset = 0, lun_count = 0, offset = 8, i;
+	u32 lun_count = 0, offset = 8, i;
 
 	buf = transport_kmap_data_sg(se_cmd);
 	if (!buf)
@@ -679,12 +679,11 @@ int target_report_luns(struct se_task *se_task)
 		 * See SPC2-R20 7.19.
 		 */
 		lun_count++;
-		if ((cdb_offset + 8) >= se_cmd->data_length)
+		if ((offset + 8) > se_cmd->data_length)
 			continue;
 
 		int_to_scsilun(deve->mapped_lun, (struct scsi_lun *)&buf[offset]);
 		offset += 8;
-		cdb_offset += 8;
 	}
 	spin_unlock_irq(&se_sess->se_node_acl->device_list_lock);