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SubjectRe: [PATCH v2] 8250_lpss: check null return when calling pci_ioremap_bar
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Hi,

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.
>
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
> ---
> drivers/tty/serial/8250/8250_lpss.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/tty/serial/8250/8250_lpss.c b/drivers/tty/serial/8250/8250_lpss.c
> index 53ca9ba6ab4b..d07e431110d9 100644
> --- a/drivers/tty/serial/8250/8250_lpss.c
> +++ b/drivers/tty/serial/8250/8250_lpss.c
> @@ -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).

> @@ -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);
> }
> #else /* CONFIG_SERIAL_8250_DMA */
> static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port) {}

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics

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