net: tg3: fix NULL pointer dereference in tg3_io_error_detected and tg3_io_slot_reset

Commit d8af4dfd8 ("net/tg3: Fix kernel crash") introduced a possible
NULL pointer dereference in tg3 driver when !netdev || !netif_running(netdev)
condition is met and netdev is NULL. Then, the jump to the 'done' label
calls dev_close() with a netdevice that is NULL. Therefore, only call
dev_close() when we have a netdevice, but one that is not running.

[ Add the same checks in tg3_io_slot_reset() per Gavin Shan - by Nithin
Nayak Sujir ]

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Gavin Shan <shangw@linux.vnet.ibm.com>
Cc: Michael Chan <mchan@broadcom.com>
Signed-off-by: Nithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: Nithin Nayak Sujir <nsujir@broadcom.com>
Signed-off-by: Michael Chan <mchan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -17796,8 +17796,10 @@ static pci_ers_result_t tg3_io_error_detected(struct pci_dev *pdev,
 
 done:
 	if (state == pci_channel_io_perm_failure) {
-		tg3_napi_enable(tp);
-		dev_close(netdev);
+		if (netdev) {
+			tg3_napi_enable(tp);
+			dev_close(netdev);
+		}
 		err = PCI_ERS_RESULT_DISCONNECT;
 	} else {
 		pci_disable_device(pdev);
@@ -17827,7 +17829,8 @@ static pci_ers_result_t tg3_io_slot_reset(struct pci_dev *pdev)
 	rtnl_lock();
 
 	if (pci_enable_device(pdev)) {
-		netdev_err(netdev, "Cannot re-enable PCI device after reset.\n");
+		dev_err(&pdev->dev,
+			"Cannot re-enable PCI device after reset.\n");
 		goto done;
 	}
 
@@ -17835,7 +17838,7 @@ static pci_ers_result_t tg3_io_slot_reset(struct pci_dev *pdev)
 	pci_restore_state(pdev);
 	pci_save_state(pdev);
 
-	if (!netif_running(netdev)) {
+	if (!netdev || !netif_running(netdev)) {
 		rc = PCI_ERS_RESULT_RECOVERED;
 		goto done;
 	}
@@ -17847,7 +17850,7 @@ static pci_ers_result_t tg3_io_slot_reset(struct pci_dev *pdev)
 	rc = PCI_ERS_RESULT_RECOVERED;
 
 done:
-	if (rc != PCI_ERS_RESULT_RECOVERED && netif_running(netdev)) {
+	if (rc != PCI_ERS_RESULT_RECOVERED && netdev && netif_running(netdev)) {
 		tg3_napi_enable(tp);
 		dev_close(netdev);
 	}