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

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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: b9b17debc6 ("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>
This commit is contained in:
Zheng Wang 2023-03-18 16:05:26 +08:00 • committed by David S. Miller
parent a8eff03545
commit 6b6bc5b8bd
1 changed files with 6 additions and 0 deletions
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6
drivers/net/ethernet/qualcomm/emac/emac.c
View file

@ -724,9 +724,15 @@ 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);