can: c_can_pci: c_can_pci_remove(): fix use-after-free

There is a UAF in c_can_pci_remove(). dev is released by
free_c_can_dev() and is used by pci_iounmap(pdev, priv->base) later.
To fix this issue, save the mmio address before releasing dev.

Fixes: 5b92da04 ("c_can_pci: generic module for C_CAN/D_CAN on PCI")
Link: https://lore.kernel.org/r/20210301024512.539039-1-ztong0001@gmail.comSigned-off-by: Tong Zhang <ztong0001@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/c_can/c_can_pci.c

@@ -239,12 +239,13 @@ static void c_can_pci_remove(struct pci_dev *pdev)
 {
 	struct net_device *dev = pci_get_drvdata(pdev);
 	struct c_can_priv *priv = netdev_priv(dev);
+	void __iomem *addr = priv->base;
 
 	unregister_c_can_dev(dev);
 
 	free_c_can_dev(dev);
 
-	pci_iounmap(pdev, priv->base);
+	pci_iounmap(pdev, addr);
 	pci_disable_msi(pdev);
 	pci_clear_master(pdev);
 	pci_release_regions(pdev);