linux-kernel - Re: [PATCH v2] 8250_lpss: check null return when calling pci_ioremap

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Message-ID: <CAHp75Ve_fLZukJ2amKCUgFkMxmvMgOEL03v1OojHcE2eVvO3bg@mail.gmail.com>
Date:   Sat, 20 Jul 2019 01:36:43 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Navid Emamdoost <navid.emamdoost@...il.com>
Cc:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        emamd001@....edu, Kangjie Lu <kjlu@....edu>, smccaman@....edu,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jslaby@...e.com>, Vinod Koul <vkoul@...nel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] 8250_lpss: check null return when calling pci_ioremap_bar

On Sat, Jul 20, 2019 at 12:45 AM Navid Emamdoost
<navid.emamdoost@...il.com> 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.
>

Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

> Signed-off-by: Navid Emamdoost <navid.emamdoost@...il.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);
> @@ -195,11 +197,15 @@ static void qrk_serial_setup_dma(struct lpss8250 *lpss, struct uart_port *port)
>
>  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) {}
> --
> 2.17.1
>


-- 
With Best Regards,
Andy Shevchenko