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

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Message-ID: <20241121094020.3679787-1-wenst@chromium.org>
Date: Thu, 21 Nov 2024 17:40:19 +0800
From: Chen-Yu Tsai <wenst@...omium.org>
To: Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Chen-Yu Tsai <wenst@...omium.org>,
	linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Klara Modin <klarasmodin@...il.com>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczyński <kwilczynski@...nel.org>,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
	stable+noautosel@...nel.org
Subject: [PATCH] PCI/pwrctl: Do not assume device node presence

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",
-- 
2.47.0.338.g60cca15819-goog