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

From: Luis Henriques
Date: Mon Dec 15 2014 - 09:30:33 EST

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


From: Andreas Noever <andreas.noever@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
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");

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