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

Andy Shevchenko
2019-07-19T13:37:45Z

On Thu, Jul 18, 2019 at 09:54:42PM -0500, 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 returning -ENOMEM (I am not sure this is the best errno, you may
> consider it as a placeholder), and subsequently changing the caller’s
> return type, and propagating the error.

Thanks for the patch, my comments below.

> chip->irq = pci_irq_vector(pdev, 0);
> chip->regs = pci_ioremap_bar(pdev, 1);
> + if (!chip->regs)
> + return -ENOMEM;

This is the same case as below, it's fine to go on without DMA support.

> chip->pdata = &qrk_serial_dma_pdata;

So, I would rather to put like this...

Hold on, I remember someone already tried to fix this [1].

I dunno why it wasn't v5, due to [2].

Also, similar to yours, but wrong [3].

Thus, please, collaborate guys, and send one compiling solution based on [1].

> /* Falling back to PIO mode if DMA probing fails */
> ret = dw_dma_probe(chip);
> if (ret)
> - return;
> + return 0;

[1]: https://www.spinics.net/lists/linux-serial/msg33965.html
[2]: https://lists.01.org/pipermail/kbuild-all/2019-March/059215.html
[3]: https://lore.kernel.org/patchwork/patch/1051000/