[PATCH 3.16 061/306] powerpc/eeh: Null check uses of eeh_pe_bus_get

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Russell Currey <ruscur@xxxxxxxxxx>

commit 04fec21c06e35b169a83e75a84a015ab4606bf5e upstream.

eeh_pe_bus_get() can return NULL if a PCI bus isn't found for a given PE.
Some callers don't check this, and can cause a null pointer dereference
under certain circumstances.

Fix this by checking NULL everywhere eeh_pe_bus_get() is called.

Fixes: 8a6b1bc70dbb ("powerpc/eeh: EEH core to handle special event")
Signed-off-by: Russell Currey <ruscur@xxxxxxxxxx>
Reviewed-by: Andrew Donnellan <andrew.donnellan@xxxxxxxxxxx>
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 arch/powerpc/kernel/eeh_driver.c          | 8 ++++++++
 arch/powerpc/platforms/powernv/eeh-ioda.c | 5 +++++
 2 files changed, 13 insertions(+)

--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -828,6 +828,14 @@ static void eeh_handle_special_event(voi
 
 				/* Notify all devices to be down */
 				bus = eeh_pe_bus_get(phb_pe);
+				if (!bus) {
+					pr_err("%s: Cannot find PCI bus for "
+					       "PHB#%d-PE#%x\n",
+					       __func__,
+					       pe->phb->global_number,
+					       pe->addr);
+					break;
+				}
 				eeh_pe_dev_traverse(pe,
 					eeh_report_failure, NULL);
 				pcibios_remove_pci_devices(bus);
--- a/arch/powerpc/platforms/powernv/eeh-ioda.c
+++ b/arch/powerpc/platforms/powernv/eeh-ioda.c
@@ -578,6 +578,11 @@ static int ioda_eeh_reset(struct eeh_pe
 		ret = ioda_eeh_phb_reset(hose, option);
 	} else {
 		bus = eeh_pe_bus_get(pe);
+		if (!bus) {
+			pr_err("%s: Cannot find PCI bus for PHB#%d-PE#%x\n",
+			       __func__, pe->phb->global_number, pe->addr);
+			return -EIO;
+		}
 		if (pci_is_root_bus(bus) ||
 		    pci_is_root_bus(bus->parent))
 			ret = ioda_eeh_root_reset(hose, option);