Re: [PATCH v12 10/10] PCI: of: Avoid np->data usage for the node changeset

[Andy Shevchenko]

On Thu, Oct 01, 2026 at 04:28:10PM +0200, Herve Codina wrote:
> of_pci_remove_node() and of_pci_remove_host_bridge_node() check
> whether the node is dynamic but not whether it has valid private data.
> 
> During the node creation, an OF changeset is used and this changeset is
> stored in np->data to be available for removal functions.
> 
> If, for instance, a PCI host bridge is created using a device-tree
> overlay, the related node will have the dynamic flag set but np->data
> will be NULL. This leads to NULL pointer dereferences.
> 
> Checking for a non-NULL np->data pointer to determine if the node has
> been created by the PCI node creation process is not enough. Indeed,
> on some platforms like PowerPC, the OF_RECONFIG_ATTACH_NODE notifier
> (e.g., in the pci_dn_reconfig_notifier() function) intercepts node
> additions and populates np->data with its own structure, such as a
> struct pci_dn. In that case, np->data is not NULL but it is not related
> to our changeset stored during the PCI node process creation.
> 
> Avoid the usage of np->data to store the changeset used during the PCI
> node creation. Store our changeset in a more relevant structure: either
> struct pci_dev when the node is created for a PCI device or struct
> pci_host_bridge when the node is created for the PCI host bridge.
> 
> With that done, no ambiguity remains on removal. Indeed, this changeset,
> if non-NULL, is the one used during PCI node creation. Check and use
> this changeset on the removal process.

...

>  void of_pci_remove_node(struct pci_dev *pdev)

>  	struct device_node *np;
>  
>  	np = pci_device_to_OF_node(pdev);
> -	if (!np || !of_node_check_flag(np, OF_DYNAMIC))
> +	if (!pdev->cset || !np)
>  		return;

Wouldn't be better to split this conditional to two?

	if (!pdev->cset)
		return;

	np = pci_device_to_OF_node(pdev);
	if (!np)
		return;

>  	fw_devlink_set_device(&np->fwnode, NULL);
>  	device_remove_of_node(&pdev->dev);
> -	of_changeset_revert(np->data);
> -	of_changeset_destroy(np->data);
> +	of_changeset_revert(pdev->cset);
> +	of_changeset_destroy(pdev->cset);
>  	of_node_put(np);
> +	kfree(pdev->cset);
> +	pdev->cset = NULL;
>  }

-- 
With Best Regards,
Andy Shevchenko