linux-kernel - Re: [PATCH] PCI/pwrctl: Do not assume device node presence

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Message-ID: <cdfab3ac-4506-4415-a70b-1eb867bb9d9f@gmail.com>
Date: Thu, 21 Nov 2024 11:42:29 +0100
From: Klara Modin <klarasmodin@...il.com>
To: Chen-Yu Tsai <wenst@...omium.org>, Bjorn Helgaas <bhelgaas@...gle.com>
Cc: linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
 Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
 Krzysztof Wilczyński <kwilczynski@...nel.org>,
 Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
 stable+noautosel@...nel.org
Subject: Re: [PATCH] PCI/pwrctl: Do not assume device node presence

On 2024-11-21 10:40, Chen-Yu Tsai wrote:
> A PCI device normally does not have a device node, since the bus is
> fully enumerable. Assuming that a device node is presence is likely
> bad.
> 
> The newly added pwrctl code assumes such and crashes with a NULL
> pointer dereference. Besides that, of_find_device_by_node(NULL)
> is likely going to return some random device.
> 
> Reported-by: Klara Modin <klarasmodin@...il.com>
> Closes: https://lore.kernel.org/linux-pci/a7b8f84d-efa6-490c-8594-84c1de9a7031@gmail.com/
> Fixes: cc70852b0962 ("PCI/pwrctl: Ensure that pwrctl drivers are probed before PCI client drivers")
> Cc: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> Cc: Krzysztof Wilczyński <kwilczynski@...nel.org>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> Cc: stable+noautosel@...nel.org         # Depends on power supply check
> Signed-off-by: Chen-Yu Tsai <wenst@...omium.org>
> ---
>   drivers/pci/bus.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
> index 98910bc0fcc4..eca72e0c3b6c 100644
> --- a/drivers/pci/bus.c
> +++ b/drivers/pci/bus.c
> @@ -405,7 +405,7 @@ void pci_bus_add_device(struct pci_dev *dev)
>   	 * before PCI client drivers.
>   	 */
>   	pdev = of_find_device_by_node(dn);
> -	if (pdev && of_pci_supply_present(dn)) {
> +	if (dn && pdev && of_pci_supply_present(dn)) {
>   		if (!device_link_add(&dev->dev, &pdev->dev,
>   				     DL_FLAG_AUTOREMOVE_CONSUMER))
>   			pci_err(dev, "failed to add device link to power control device %s\n",

Thanks for the fix,
Tested-by: Klara Modin <klarasmodin@...il.com>