Re: [PATCH 4.4 74/76] serial: 8250_pci: Detach low-level driver during PCI error recovery

[Ben Hutchings]

On Tue, 2017-03-28 at 14:31 +0200, Greg Kroah-Hartman wrote:
[...]
>  static void serial8250_io_resume(struct pci_dev *dev)
>  {
>  	struct serial_private *priv = pci_get_drvdata(dev);
> +	const struct pciserial_board *board;
>  
> -	if (priv)
> -		pciserial_resume_ports(priv);
> +	if (!priv)
> +		return;
> +
> +	board = priv->board;
> +	kfree(priv);
> +	priv = pciserial_init_ports(dev, board);
> +
> +	if (!IS_ERR(priv)) {
> +		pci_set_drvdata(dev, priv);
> +	}
>  }

On error, this leaves drvdata as a dangling pointer.  Removing the
device or driver will then cause a use-after-free.  (And setting drvdata
to NULL isn't enough to fix this as there is no null pointer check in
pciserial_remove_ports().)

Ben.

-- 
Ben Hutchings
Software Developer, Codethink Ltd.