net: arcnet: com20020 fix error handling

There are two issues when handling error case in com20020pci_probe()

1. priv might be not initialized yet when calling com20020pci_remove()
from com20020pci_probe(), since the priv is set at the very last but it
can jump to error handling in the middle and priv remains NULL.
2. memory leak - the net device is allocated in alloc_arcdev but not
properly released if error happens in the middle of the big for loop

[    1.529110] BUG: kernel NULL pointer dereference, address: 0000000000000008
[    1.531447] RIP: 0010:com20020pci_remove+0x15/0x60 [com20020_pci]
[    1.536805] Call Trace:
[    1.536939]  com20020pci_probe+0x3f2/0x48c [com20020_pci]
[    1.537226]  local_pci_probe+0x48/0x80
[    1.539918]  com20020pci_init+0x3f/0x1000 [com20020_pci]

Signed-off-by: Tong Zhang <ztong0001@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/arcnet/com20020-pci.c

@@ -127,6 +127,8 @@ static int com20020pci_probe(struct pci_dev *pdev,
 	int i, ioaddr, ret;
 	struct resource *r;
 
+	ret = 0;
+
 	if (pci_enable_device(pdev))
 		return -EIO;
 
@@ -139,6 +141,8 @@ static int com20020pci_probe(struct pci_dev *pdev,
 	priv->ci = ci;
 	mm = &ci->misc_map;
 
+	pci_set_drvdata(pdev, priv);
+
 	INIT_LIST_HEAD(&priv->list_dev);
 
 	if (mm->size) {
@@ -161,7 +165,7 @@ static int com20020pci_probe(struct pci_dev *pdev,
 		dev = alloc_arcdev(device);
 		if (!dev) {
 			ret = -ENOMEM;
-			goto out_port;
+			break;
 		}
 		dev->dev_port = i;
 
@@ -178,7 +182,7 @@ static int com20020pci_probe(struct pci_dev *pdev,
 			pr_err("IO region %xh-%xh already allocated\n",
 			       ioaddr, ioaddr + cm->size - 1);
 			ret = -EBUSY;
-			goto out_port;
+			goto err_free_arcdev;
 		}
 
 		/* Dummy access after Reset
@@ -216,18 +220,18 @@ static int com20020pci_probe(struct pci_dev *pdev,
 		if (arcnet_inb(ioaddr, COM20020_REG_R_STATUS) == 0xFF) {
 			pr_err("IO address %Xh is empty!\n", ioaddr);
 			ret = -EIO;
-			goto out_port;
+			goto err_free_arcdev;
 		}
 		if (com20020_check(dev)) {
 			ret = -EIO;
-			goto out_port;
+			goto err_free_arcdev;
 		}
 
 		card = devm_kzalloc(&pdev->dev, sizeof(struct com20020_dev),
 				    GFP_KERNEL);
 		if (!card) {
 			ret = -ENOMEM;
-			goto out_port;
+			goto err_free_arcdev;
 		}
 
 		card->index = i;
@@ -253,29 +257,29 @@ static int com20020pci_probe(struct pci_dev *pdev,
 
 		ret = devm_led_classdev_register(&pdev->dev, &card->tx_led);
 		if (ret)
-			goto out_port;
+			goto err_free_arcdev;
 
 		ret = devm_led_classdev_register(&pdev->dev, &card->recon_led);
 		if (ret)
-			goto out_port;
+			goto err_free_arcdev;
 
 		dev_set_drvdata(&dev->dev, card);
 
 		ret = com20020_found(dev, IRQF_SHARED);
 		if (ret)
-			goto out_port;
+			goto err_free_arcdev;
 
 		devm_arcnet_led_init(dev, dev->dev_id, i);
 
 		list_add(&card->list, &priv->list_dev);
+		continue;
+
+err_free_arcdev:
+		free_arcdev(dev);
+		break;
 	}
-
-	pci_set_drvdata(pdev, priv);
-
-	return 0;
-
-out_port:
-	com20020pci_remove(pdev);
+	if (ret)
+		com20020pci_remove(pdev);
 	return ret;
 }