From: Arthur Kiyanovski <akiyano@amazon.com>
Date: Mon, 19 Nov 2018 12:05:21 +0200
Subject: net: ena: fix crash during ena_remove()
Patch-mainline: v4.20-rc4
Git-commit: 58a54b9c62e206b8d5f6e59020bcb178fc271d8e
References: bsc#1111696 bsc#1117561

In ena_remove() we have the following stack call:
ena_remove()
  unregister_netdev()
  ena_destroy_device()
    netif_carrier_off()

Calling netif_carrier_off() causes linkwatch to try to handle the
link change event on the already unregistered netdev, which leads
to a read from an unreadable memory address.

This patch switches the order of the two functions, so that
netif_carrier_off() is called on a regiestered netdev.

To accomplish this fix we also had to:
1. Remove the set bit ENA_FLAG_TRIGGER_RESET
2. Add a sanitiy check in ena_close()
both to prevent double device reset (when calling unregister_netdev()
ena_close is called, but the device was already deleted in
ena_destroy_device()).
3. Set the admin_queue running state to false to avoid using it after
device was reset (for example when calling ena_destroy_all_io_queues()
right after ena_com_dev_reset() in ena_down)

Fixes: 944b28aa2982 ("net: ena: fix missing lock during device destruction")
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/amazon/ena/ena_netdev.c |   21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

--- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
+++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
@@ -1849,6 +1849,8 @@ static void ena_down(struct ena_adapter
 		rc = ena_com_dev_reset(adapter->ena_dev, adapter->reset_reason);
 		if (rc)
 			dev_err(&adapter->pdev->dev, "Device reset failed\n");
+		/* stop submitting admin commands on a device that was reset */
+		ena_com_set_admin_running_state(adapter->ena_dev, false);
 	}
 
 	ena_destroy_all_io_queues(adapter);
@@ -1915,6 +1917,9 @@ static int ena_close(struct net_device *
 
 	netif_dbg(adapter, ifdown, netdev, "%s\n", __func__);
 
+	if (!test_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags))
+		return 0;
+
 	if (test_bit(ENA_FLAG_DEV_UP, &adapter->flags))
 		ena_down(adapter);
 
@@ -2613,9 +2618,7 @@ static void ena_destroy_device(struct en
 		ena_down(adapter);
 
 	/* Stop the device from sending AENQ events (in case reset flag is set
-	 *  and device is up, ena_close already reset the device
-	 * In case the reset flag is set and the device is up, ena_down()
-	 * already perform the reset, so it can be skipped.
+	 *  and device is up, ena_down() already reset the device.
 	 */
 	if (!(test_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags) && dev_up))
 		ena_com_dev_reset(adapter->ena_dev, adapter->reset_reason);
@@ -3453,6 +3456,8 @@ err_rss:
 	ena_com_rss_destroy(ena_dev);
 err_free_msix:
 	ena_com_dev_reset(ena_dev, ENA_REGS_RESET_INIT_ERR);
+	/* stop submitting admin commands on a device that was reset */
+	ena_com_set_admin_running_state(ena_dev, false);
 	ena_free_mgmnt_irq(adapter);
 	ena_disable_msix(adapter);
 err_worker_destroy:
@@ -3525,18 +3530,12 @@ static void ena_remove(struct pci_dev *p
 
 	cancel_work_sync(&adapter->reset_task);
 
-	unregister_netdev(netdev);
-
-	/* If the device is running then we want to make sure the device will be
-	 * reset to make sure no more events will be issued by the device.
-	 */
-	if (test_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags))
-		set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);
-
 	rtnl_lock();
 	ena_destroy_device(adapter, true);
 	rtnl_unlock();
 
+	unregister_netdev(netdev);
+
 	free_netdev(netdev);
 
 	ena_com_rss_destroy(ena_dev);