Re: [PATCH 13/20] alpha/PCI: Clean up __pci_mmap_fits()

Krzysztof Wilczyński
2026-04-10T11:21:38Z

Hello,

> > Currently, __pci_mmap_fits() computes the BAR size using
> > pci_resource_len() - 1, which wraps to a large value when the
> > BAR length is zero, causing the bounds check to incorrectly
> > succeed.
> >
> > Thus, add an early return for empty resources.
> >
> > Also, remove the WARN() that fires when userspace attempts to
> > mmap beyond the BAR bounds. The check still returns 0 to reject
> > the mapping, but the warning is excessive for normal operation.
> >
> > A similar warning was removed from the PCI core in the commit
> > 3b519e4ea618 ("PCI: fix size checks for mmap() on /proc/bus/pci files").
>
> This looks like entirely separate two changes to me which just happen
> within the same context.

True. I could split this into two separate patches. However, the early
return is so trivial, that I decided to keep it here, in lieu of that the
linked patch did, too.

Thoughts?

Thank you!

Krzysztof