scsi: qla2xxx: fix a potential NULL pointer dereference

commit 35a79a63 upstream.

alloc_workqueue is not checked for errors and as a result a potential
NULL dereference could occur.

Link: https://lore.kernel.org/r/1568824618-4366-1-git-send-email-allen.pais@oracle.comSigned-off-by: Allen Pais <allen.pais@oracle.com>
Reviewed-by: Martin Wilck <mwilck@suse.com>
Acked-by: Himanshu Madhani <hmadhani@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
[Ajay: Rewrote this patch for v4.9.y, as 4.9.y codebase is different from mainline]
Signed-off-by: Ajay Kaher <akaher@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/scsi/qla2xxx/qla_os.c

@@ -451,6 +451,12 @@ static int qla25xx_setup_mode(struct scsi_qla_host *vha)
 		goto fail;
 	}
 	if (ql2xmultique_tag) {
+		ha->wq = alloc_workqueue("qla2xxx_wq", WQ_MEM_RECLAIM, 1);
+		if (unlikely(!ha->wq)) {
+			ql_log(ql_log_warn, vha, 0x01e0,
+			    "Failed to alloc workqueue.\n");
+			goto fail;
+		}
 		/* create a request queue for IO */
 		options |= BIT_7;
 		req = qla25xx_create_req_que(ha, options, 0, 0, -1,
@@ -458,9 +464,8 @@ static int qla25xx_setup_mode(struct scsi_qla_host *vha)
 		if (!req) {
 			ql_log(ql_log_warn, vha, 0x00e0,
 			    "Failed to create request queue.\n");
-			goto fail;
+			goto fail2;
 		}
-		ha->wq = alloc_workqueue("qla2xxx_wq", WQ_MEM_RECLAIM, 1);
 		vha->req = ha->req_q_map[req];
 		options |= BIT_1;
 		for (ques = 1; ques < ha->max_rsp_queues; ques++) {
@@ -468,7 +473,7 @@ static int qla25xx_setup_mode(struct scsi_qla_host *vha)
 			if (!ret) {
 				ql_log(ql_log_warn, vha, 0x00e8,
 				    "Failed to create response queue.\n");
-				goto fail2;
+				goto fail3;
 			}
 		}
 		ha->flags.cpu_affinity_enabled = 1;
@@ -482,11 +487,13 @@ static int qla25xx_setup_mode(struct scsi_qla_host *vha)
 		    ha->max_rsp_queues, ha->max_req_queues);
 	}
 	return 0;
-fail2:
+
+fail3:
 	qla25xx_delete_queues(vha);
-	destroy_workqueue(ha->wq);
-	ha->wq = NULL;
 	vha->req = ha->req_q_map[0];
+fail2:
+        destroy_workqueue(ha->wq);
+        ha->wq = NULL;
 fail:
 	ha->mqenable = 0;
 	kfree(ha->req_q_map);