[PATCH] PCI: of_property: Omit 'bus-range' property if no secondary bus

[Bo Sun <bo.sun.cn@windriver.com>]

The previous implementation of of_pci_add_properties() and
of_pci_prop_bus_range() assumed that a valid secondary bus is always
present, which can be problematic in cases where no bus numbers are
assigned for a secondary bus. This patch introduces a check for a valid
secondary bus and omits the 'bus-range' property if it is not available,
preventing dereferencing the NULL pointer.

Cc: stable@vger.kernel.org
Fixes: 407d1a51921e ("PCI: Create device tree node for bridge")
Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Bo Sun <bo.sun.cn@windriver.com>
---
 drivers/pci/of_property.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
index 75a358f73e69..cade01ea6e68 100644
--- a/drivers/pci/of_property.c
+++ b/drivers/pci/of_property.c
@@ -95,6 +95,9 @@ static int of_pci_prop_bus_range(struct pci_dev *pdev,
 				 struct of_changeset *ocs,
 				 struct device_node *np)
 {
+	if (!pdev->subordinate)
+		return -EINVAL;
+
 	u32 bus_range[] = { pdev->subordinate->busn_res.start,
 			    pdev->subordinate->busn_res.end };