scsi: hptiop: Use struct_size() helper in code related to struct hpt_iop_request_scsi_command

Prefer struct_size() over open-coded versions of idiom:

sizeof(struct-with-flex-array) + sizeof(typeof-flex-array-elements) * count

where count is the max number of items the flexible array is supposed to
contain.

Link: https://github.com/KSPP/linux/issues/160
Link: https://lore.kernel.org/r/54e2bb1e39b21394c5a90cacbadfb6136b012788.1663865333.git.gustavoars@kernel.orgReviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/hptiop.c

@@ -1044,9 +1044,7 @@ static int hptiop_queuecommand_lck(struct scsi_cmnd *scp)
 	req->channel = scp->device->channel;
 	req->target = scp->device->id;
 	req->lun = scp->device->lun;
-	req->header.size = cpu_to_le32(
-				sizeof(struct hpt_iop_request_scsi_command)
-				 + sg_count * sizeof(struct hpt_iopsg));
+	req->header.size = cpu_to_le32(struct_size(req, sg_list, sg_count));
 
 	memcpy(req->cdb, scp->cmnd, sizeof(req->cdb));
 	hba->ops->post_req(hba, _req);
@@ -1396,8 +1394,8 @@ static int hptiop_probe(struct pci_dev *pcidev, const struct pci_device_id *id)
 	host->cmd_per_lun = le32_to_cpu(iop_config.max_requests);
 	host->max_cmd_len = 16;
 
-	req_size = sizeof(struct hpt_iop_request_scsi_command)
-		+ sizeof(struct hpt_iopsg) * hba->max_sg_descriptors;
+	req_size = struct_size((struct hpt_iop_request_scsi_command *)0,
+			       sg_list, hba->max_sg_descriptors);
 	if ((req_size & 0x1f) != 0)
 		req_size = (req_size + 0x1f) & ~0x1f;