Re: [PATCH] serial: 8250_lpss: Fix missing check for return value of pci_get_slot()

[Andy Shevchenko]

On Wed, Jun 14, 2023 at 08:32:26AM -0700, Chenyuan Mi wrote:
> The pci_get_slot() function may return NULL, which may
> cause null pointer deference, and most other callsites of
> pci_get_slot() do Null check. Add Null check for return
> value of pci_get_slot().
> 
> Found by our static analysis tool.

...

>  	dma_dev = pci_get_slot(pdev->bus, PCI_DEVFN(PCI_SLOT(pdev->devfn), 0));
> +	if (!dma_dev)
> +		return -ENODEV;

This adds (almost) a dead code. The function 0 must be present in accordance
with the PCI specification (even earliest version of it state that).
If pci_get_slot() returns a NULL, in this case it means that something, much
bigger issue, happens and this check won't help us to do anything anyway.

-- 
With Best Regards,
Andy Shevchenko