net: qcom/emac: Fix use after free bug in emac_remove due to race condition

[ Upstream commit 6b6bc5b8bd2d4ca9e1efa9ae0f98a0b0687ace75 ]

In emac_probe, &adpt->work_thread is bound with
emac_work_thread. Then it will be started by timeout
handler emac_tx_timeout or a IRQ handler emac_isr.

If we remove the driver which will call emac_remove
  to make cleanup, there may be a unfinished work.

The possible sequence is as follows:

Fix it by finishing the work before cleanup in the emac_remove
and disable timeout response.

CPU0                  CPU1

                    |emac_work_thread
emac_remove         |
free_netdev         |
kfree(netdev);      |
                    |emac_reinit_locked
                    |emac_mac_down
                    |//use netdev
Fixes: 537813f6160a ("net: emac: emac gigabit ethernet controller driver")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/net/ethernet/qualcomm/emac/emac.c b/drivers/net/ethernet/qualcomm/emac/emac.c
index 5c199d2516d475b1650ccc5912989d903aaf405f..5fe28dec60c1d73c6a35696acabd22f07b3195c2 100644 (file)
--- a/drivers/net/ethernet/qualcomm/emac/emac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac.c
@@ -738,9 +738,15 @@ static int emac_remove(struct platform_device *pdev)
        struct net_device *netdev = dev_get_drvdata(&pdev->dev);
        struct emac_adapter *adpt = netdev_priv(netdev);
 
+       netif_carrier_off(netdev);
+       netif_tx_disable(netdev);
+
        unregister_netdev(netdev);
        netif_napi_del(&adpt->rx_q.napi);
 
+       free_irq(adpt->irq.irq, &adpt->irq);
+       cancel_work_sync(&adpt->work_thread);
+
        emac_clks_teardown(adpt);
 
        put_device(&adpt->phydev->mdio.dev);