Re: [PATCH] PCI/sysfs: Check IORESOURCE_DISABLED in resource mmap handler

[Ilpo Järvinen]

On Tue, 12 May 2026, Krzysztof Wilczyński wrote:

> Hello,
> 
> > pci_mmap_resource() does not check IORESOURCE_DISABLED before mapping
> > a PCI BAR resource into userspace. This allows new mmaps to succeed
> > even after a device has been marked disabled or soft-unplugged by the
> > driver to prevent further access.
> 
> Which driver disables resources?  Would this be some Amazon-specific thing
> you are trying to fix?  Or are you just manually disabling a given device
> using sysfs, or something like this?
> 
> For "soft-unplugged" device we have pci_dev_set_disconnected(), but this
> does not check current flags set.
> 
> What is your use case here?
> 
> > Add the check to return -ENODEV when the resource is disabled, blocking
> > new userspace mmaps of BAR resources after device removal.
> > 
> > Tested by marking the PCI BAR resource as disabled and verifying that
> > a subsequent mmap attempt fails with -ENODEV.
> 
> Can you explain how did you do this?
> 
> > @@ -1089,6 +1089,9 @@ static int pci_mmap_resource(struct kobject *kobj, const struct bin_attribute *a
> >  	if (ret)
> >  		return ret;
> >  
> > +	if (res->flags & IORESOURCE_DISABLED)
> > +		return -ENODEV;
> > +
> 
> This probably would be better if it checked IORESOURCE_DISABLED and
> IORESOURCE_UNSET, but then probably using resource_assigned() would
> be even better.

Yes, resource_assigned() makes more sense.

When considering Krzysztof's sysfs rework series in pci/sysfs, this all 
should be handled in .is_visible and not in pci_mmap_resource().

Also (FYI), alpha has its own pci_mmap_resource() (IIRC, it still has it 
even after Krzysztof's series).

-- 
 i.