[PATCH 3.16.y-ckt 167/168] PCI: pciehp: Prevent NULL dereference during probe

[Luis Henriques]

3.16.7-ckt3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andreas Noever <andreas.noever at gmail.com>

commit bceee4a97eb58bd0e80e39eff11b506ddd9e7ad3 upstream.

pciehp assumes that dev->subordinate, the struct pci_bus for a bridge's
secondary bus, exists.  But we do not create that bus if we run out of bus
numbers during enumeration.  This leads to a NULL dereference in
init_slot() (and other places).

Change pciehp_probe() to return -ENODEV when no secondary bus is present.

Signed-off-by: Andreas Noever <andreas.noever at gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/pci/hotplug/pciehp_core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index a2297db80813..07aa722bb12c 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -255,6 +255,13 @@ static int pciehp_probe(struct pcie_device *dev)
 	else if (pciehp_acpi_slot_detection_check(dev->port))
 		goto err_out_none;
 
+	if (!dev->port->subordinate) {
+		/* Can happen if we run out of bus numbers during probe */
+		dev_err(&dev->device,
+			"Hotplug bridge without secondary bus, ignoring\n");
+		goto err_out_none;
+	}
+
 	ctrl = pcie_init(dev);
 	if (!ctrl) {
 		dev_err(&dev->device, "Controller initialization failed\n");
-- 
2.1.3