From: Russell Currey <[email protected]>

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

===============

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 <[email protected]>
Reviewed-by: Andrew Donnellan <[email protected]>
Signed-off-by: Michael Ellerman <[email protected]>
Signed-off-by: Jiri Slaby <[email protected]>
---
 arch/powerpc/kernel/eeh_driver.c          | 8 ++++++++
 arch/powerpc/platforms/powernv/eeh-ioda.c | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index d3a132c9127c..33d998fda24e 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -697,6 +697,14 @@ static void eeh_handle_special_event(void)
 
                                /* 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);
diff --git a/arch/powerpc/platforms/powernv/eeh-ioda.c 
b/arch/powerpc/platforms/powernv/eeh-ioda.c
index b91083370bc6..605a2f07618e 100644
--- a/arch/powerpc/platforms/powernv/eeh-ioda.c
+++ b/arch/powerpc/platforms/powernv/eeh-ioda.c
@@ -493,6 +493,11 @@ static int ioda_eeh_reset(struct eeh_pe *pe, int option)
                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);
-- 
2.10.2

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