Re: [PATCH v2] 8250_lpss: check null return when calling pci_ioremap_bar

Andy Shevchenko
2019-07-26T11:57:53Z

On Fri, Jul 26, 2019 at 01:32:21PM +0200, Bartlomiej Zolnierkiewicz wrote:
> On 7/19/19 7:48 PM, Navid Emamdoost wrote:
> > pci_ioremap_bar may return null. This is eventually de-referenced at
> > drivers/dma/dw/core.c:1154 and drivers/dma/dw/core.c:1168. A null check
> > is needed to prevent null de-reference. I am adding the check and in case
> > of failure. Thanks to Andy Shevchenko for the hint on the necessity of
> > pci_iounmap when exiting.

> > @@ -169,10 +169,12 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
> > struct pci_dev *pdev = to_pci_dev(port->dev);
> > int ret;
> >
> > + chip->pdata = &qrk_serial_dma_pdata;
> > chip->dev = &pdev->dev;
> > chip->irq = pci_irq_vector(pdev, 0);
> > chip->regs = pci_ioremap_bar(pdev, 1);
> > - chip->pdata = &qrk_serial_dma_pdata;
> > + if (!chip->regs)
> > + return;
> >
> > /* Falling back to PIO mode if DMA probing fails */
> > ret = dw_dma_probe(chip);
>
> pci_iounmap() should also be called on dw_dma_probe() failure (in such
> case param->dma_dev is NULL so pci_iounmap() in qrk_serial_exit_dma()
> won't be called during exit).

Oh, yes, good catch!
Navid, can you send a follow up fix?

> > @@ -195,11 +197,15 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
> > pci_iounmap
> > static void qrk_serial_exit_dma(struct lpss8250 *lpss)
> > {
> > + struct dw_dma_chip *chip = &lpss->dma_chip;
> > struct dw_dma_slave *param = &lpss->dma_param;
> >
> > if (!param->dma_dev)
> > return;
> > - dw_dma_remove(&lpss->dma_chip);
> > +
> > + dw_dma_remove(chip);
> > +
> > + pci_iounmap(to_pci_dev(chip->dev), chip->regs);
> > }