Re: [PATCH v3 5/9] agp/via: don't rely on address of pci_device_id

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] When a device binds via `driver_override`, the PCI core passes a generic `pci_device_id_any` struct with `driver_data` set to 0. Passing this NULL pointer to the `%s` format specifier results in an unhandled `(null)` log output.
--

commit cefd4bbcd02b1f8d8a6df6f9aa562b23cee64272
Author: Gary Guo <gary@garyguo.net>

agp/via: don't rely on address of pci_device_id
    
Address of pci_device_id cannot be relied on due to presence of dynamic ID
and driver_override. Use driver_data instead.

> diff --git a/drivers/char/agp/via-agp.c b/drivers/char/agp/via-agp.c
> index 8b19a5d1a09b4..ab3b73dd080af 100644
> --- a/drivers/char/agp/via-agp.c
> +++ b/drivers/char/agp/via-agp.c
[ ... ]
> @@ -437,17 +239,14 @@ static void check_via_agp3 (struct agp_bridge_data *bridge)
>  
>  static int agp_via_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  {
> -	struct agp_device_ids *devs = via_agp_device_ids;
>  	struct agp_bridge_data *bridge;
> -	int j = 0;
>  	u8 cap_ptr;
>  
>  	cap_ptr = pci_find_capability(pdev, PCI_CAP_ID_AGP);
>  	if (!cap_ptr)
>  		return -ENODEV;
>  
> -	j = ent - agp_via_pci_table;
> -	printk (KERN_INFO PFX "Detected VIA %s chipset\n", devs[j].chipset_name);
> +	dev_info(&pdev->dev, "Detected VIA %s chipset\n", (const char *)ent->driver_data);

[Severity: Low]
Could this result in printing a (null) value to the kernel log?

If an administrator forces binding of the driver to a device using the sysfs
driver_override feature, the PCI core passes a generic pci_device_id_any struct
with driver_data set to 0.

Passing this NULL pointer to the %s format specifier in dev_info() would
print (null) in the kernel logs instead of a valid string. Is it possible
to check ent->driver_data for NULL before attempting to print it, or fall back
to a default string?

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260706-pci_id_fix-v3-0-2d48fc025acc@garyguo.net?part=5