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From:   Zheng Wang <zyytlz.wz@163.com>
To:     davem@davemloft.net
Cc:     horatiu.vultur@microchip.com, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org, hackerzheng666@gmail.com,
        1395428693sheep@gmail.com, alex000young@gmail.com,
        Zheng Wang <zyytlz.wz@163.com>
Subject: [PATCH net v3] net: ethernet: fix use after free bug in ns83820_remove_one  due to race condition
Date:   Mon, 17 Apr 2023 09:31:07 +0800
Message-Id: <20230417013107.360888-1-zyytlz.wz@163.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

In ns83820_init_one, dev->tq_refill was bound with queue_refill.

If irq happens, it will call ns83820_irq->ns83820_do_isr.
Then it invokes tasklet_schedule(&dev->rx_tasklet) to start
rx_action function. And rx_action will call ns83820_rx_kick
and finally start queue_refill function.

If we remove the driver without finishing the work, there
may be a race condition between ndev, which may cause UAF
bug.

CPU0                  CPU1

                     |queue_refill
ns83820_remove_one   |
free_netdev	 		 |
put_device			 |
free ndev			 |
                     |rx_refill
                     |//use ndev

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
v3:
- add tasklet_kill to stop more task scheduling suggested by
Horatiu Vultur
v2:
- cancel the work after unregister_netdev to make sure there
is no more request suggested by Jakub Kicinski
---
 drivers/net/ethernet/natsemi/ns83820.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/net/ethernet/natsemi/ns83820.c b/drivers/net/ethernet/natsemi/ns83820.c
index 998586872599..af597719795d 100644
--- a/drivers/net/ethernet/natsemi/ns83820.c
+++ b/drivers/net/ethernet/natsemi/ns83820.c
@@ -2208,8 +2208,14 @@ static void ns83820_remove_one(struct pci_dev *pci_dev)
 
 	ns83820_disable_interrupts(dev); /* paranoia */
 
+	netif_carrier_off(ndev);
+	netif_tx_disable(ndev);
+
 	unregister_netdev(ndev);
 	free_irq(dev->pci_dev->irq, ndev);
+	tasklet_kill(&dev->rx_tasklet);
+	cancel_work_sync(&dev->tq_refill);
+
 	iounmap(dev->base);
 	dma_free_coherent(&dev->pci_dev->dev, 4 * DESC_SIZE * NR_TX_DESC,
 			  dev->tx_descs, dev->tx_phy_descs);
-- 
2.25.1