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: b9b17debc69d ("net: emac: emac gigabit ethernet controller driver")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
v2:
- cancel the work after unregister_netdev suggested by Jakub
---
 drivers/net/ethernet/qualcomm/emac/emac.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/qualcomm/emac/emac.c b/drivers/net/ethernet/qualcomm/emac/emac.c
index 3115b2c12898..eaa50050aa0b 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac.c
@@ -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);
-- 
2.25.1

Hello:

This patch was applied to netdev/net.git (main)
by David S. Miller <davem@davemloft.net>:

On Sat, 18 Mar 2023 16:05:26 +0800 you wrote:
> 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.
> 
> [...]

Here is the summary with links:
  - [net,v2] net: qcom/emac: Fix use after free bug in emac_remove due to race condition
    https://git.kernel.org/netdev/net/c/6b6bc5b8bd2d

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

On Mon, 20 Mar 2023 09:20:17 +0000 patchwork-bot+netdevbpf@kernel.org
wrote:
> Here is the summary with links:
>   - [net,v2] net: qcom/emac: Fix use after free bug in emac_remove due to race condition
>     https://git.kernel.org/netdev/net/c/6b6bc5b8bd2d

Don't think this is correct FWIW, randomly shutting things down without
holding any locks and before unregister_netdev() is called has got to
be racy. Oh, eh.