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PCI: of_property: Omit bus properties without a subordinate bus

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A bridge (a device with a Type 1 header) may not have a secondary bus
allocated (pdev->subordinate), e.g., if there are no available bus numbers
or the bridge secondary/subordinate bus numbers are not writable.

The dynamic OF helpers of_pci_prop_bus_range() and of_pci_prop_intr_map()
dereference pdev->subordinate without checking it.  When
CONFIG_PCI_DYNAMIC_OF_NODES is enabled, this can cause a NULL pointer
dereference and early boot hang.

Generate 'bus-range' and 'interrupt-map' properties only when a subordinate
bus exists.  Keep the node and its remaining properties for bridges without
one.

The problem was latent since 407d1a5192 ("PCI: Create device tree node
for bridge"), but wasn't reachable until 1f34072441 ("PCI: of: Create
device tree PCI host bridge node"), which appeared in v6.15.  Before
1f34072441, of_pci_make_dev_node() returned early because the parent OF
node was missing.

Fixes: 407d1a5192 ("PCI: Create device tree node for bridge")
Signed-off-by: Angel J <iamanaws@httpd.dev>
[bhelgaas: move pdev->subordinate test to callees, commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: stable@vger.kernel.org	# v6.6+
Link: https://patch.msgid.link/20260918195540.GA1187209@bhelgaas
This commit is contained in:
Angel J 2026-09-18 14:55:40 -05:00 committed by Bjorn Helgaas
parent d58384c227
commit 8805840aad
1 changed files with 9 additions and 2 deletions
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11
drivers/pci/of_property.c
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@ -95,9 +95,13 @@ static int of_pci_prop_bus_range(struct pci_dev *pdev,
struct of_changeset *ocs,
struct device_node *np)
{
u32 bus_range[] = { pdev->subordinate->busn_res.start,
pdev->subordinate->busn_res.end };
u32 bus_range[2];
if (!pdev->subordinate)
return 0;
bus_range[0] = pdev->subordinate->busn_res.start;
bus_range[1] = pdev->subordinate->busn_res.end;
return of_changeset_add_prop_u32_array(ocs, np, "bus-range", bus_range,
ARRAY_SIZE(bus_range));
}
@ -220,6 +224,9 @@ static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
int ret;
u8 pin;
if (!pdev->subordinate)
return 0;
pnode = pci_device_to_OF_node(pdev->bus->self);
if (!pnode)
pnode = pci_bus_to_OF_node(pdev->bus);