[PATCH 4.8 040/140] powerpc/eeh: Null check uses of eeh_pe_bus_get

[Greg Kroah-Hartman]

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

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

From: Russell Currey <rus...@russell.cc>

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 <rus...@russell.cc>
Reviewed-by: Andrew Donnellan <andrew.donnel...@au1.ibm.com>
Signed-off-by: Michael Ellerman <m...@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/powerpc/kernel/eeh_driver.c             |    8 ++++++++
 arch/powerpc/platforms/powernv/eeh-powernv.c |    5 +++++
 2 files changed, 13 insertions(+)

--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -994,6 +994,14 @@ static void eeh_handle_special_event(voi
                                /* Notify all devices to be down */
                                eeh_pe_state_clear(pe, EEH_PE_PRI_BUS);
                                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);
                                pci_hp_remove_devices(bus);
--- a/arch/powerpc/platforms/powernv/eeh-powernv.c
+++ b/arch/powerpc/platforms/powernv/eeh-powernv.c
@@ -1091,6 +1091,11 @@ static int pnv_eeh_reset(struct eeh_pe *
        }
 
        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 (pe->type & EEH_PE_VF)
                return pnv_eeh_reset_vf_pe(pe, option);