diff --git a/drivers/target/target_core_spc.c b/drivers/target/target_core_spc.c
index 556ea1b2cdd8..f87d4cef6d39 100644
--- a/drivers/target/target_core_spc.c
+++ b/drivers/target/target_core_spc.c
@@ -1203,17 +1203,13 @@ sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
 	struct se_dev_entry *deve;
 	struct se_session *sess = cmd->se_sess;
 	struct se_node_acl *nacl;
+	struct scsi_lun slun;
 	unsigned char *buf;
 	u32 lun_count = 0, offset = 8;
-
-	if (cmd->data_length < 16) {
-		pr_warn("REPORT LUNS allocation length %u too small\n",
-			cmd->data_length);
-		return TCM_INVALID_CDB_FIELD;
-	}
+	__be32 len;
 
 	buf = transport_kmap_data_sg(cmd);
-	if (!buf)
+	if (cmd->data_length && !buf)
 		return TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
 
 	/*
@@ -1234,10 +1230,12 @@ sense_reason_t spc_emulate_report_luns(struct se_cmd *cmd)
 		 * See SPC2-R20 7.19.
 		 */
 		lun_count++;
-		if ((offset + 8) > cmd->data_length)
+		if (offset >= cmd->data_length)
 			continue;
 
-		int_to_scsilun(deve->mapped_lun, (struct scsi_lun *)&buf[offset]);
+		int_to_scsilun(deve->mapped_lun, &slun);
+		memcpy(buf + offset, &slun,
+		       min(8u, cmd->data_length - offset));
 		offset += 8;
 	}
 	rcu_read_unlock();
@@ -1250,16 +1248,18 @@ done:
 	 * If no LUNs are accessible, report virtual LUN 0.
 	 */
 	if (lun_count == 0) {
-		int_to_scsilun(0, (struct scsi_lun *)&buf[offset]);
+		int_to_scsilun(0, &slun);
+		if (cmd->data_length > 8)
+			memcpy(buf + offset, &slun,
+			       min(8u, cmd->data_length - offset));
 		lun_count = 1;
 	}
 
-	lun_count *= 8;
-	buf[0] = ((lun_count >> 24) & 0xff);
-	buf[1] = ((lun_count >> 16) & 0xff);
-	buf[2] = ((lun_count >> 8) & 0xff);
-	buf[3] = (lun_count & 0xff);
-	transport_kunmap_data_sg(cmd);
+	if (buf) {
+		len = cpu_to_be32(lun_count * 8);
+		memcpy(buf, &len, min_t(int, sizeof len, cmd->data_length));
+		transport_kunmap_data_sg(cmd);
+	}
 
 	target_complete_cmd_with_length(cmd, GOOD, 8 + lun_count * 8);
 	return 0;