PCI: pciehp: Prevent NULL dereference during probe

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@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: stable@vger.kernel.org	# v3.2+

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/pci/hotplug/pciehp_core.c b/drivers/pci/hotplug/pciehp_core.c
index 07aa722bb12c..3a5e7e28b874 100644
--- a/drivers/pci/hotplug/pciehp_core.c
+++ b/drivers/pci/hotplug/pciehp_core.c
@@ -262,6 +262,13 @@ static int pciehp_probe(struct pcie_device *dev)
                 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");