powerpc/eeh: Null check uses of eeh_pe_bus_get

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")
Cc: stable@vger.kernel.org # v3.11+
Signed-off-by: Russell Currey <ruscur@russell.cc>
Reviewed-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

2 files changed, 13 insertions, 0 deletions

diff --git a/arch/powerpc/kernel/eeh_driver.c b/arch/powerpc/kernel/eeh_driver.c
index 5f36e8a70daa..29aa8d1ce273 100644
--- a/arch/powerpc/kernel/eeh_driver.c
+++ b/arch/powerpc/kernel/eeh_driver.c
@@ -994,6 +994,14 @@ static void eeh_handle_special_event(void)
                                 /* 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);
diff --git a/arch/powerpc/platforms/powernv/eeh-powernv.c b/arch/powerpc/platforms/powernv/eeh-powernv.c
index 86544ea85dc3..cb08e6aaf9bd 100644
--- 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 *pe, int option)
         }
 
         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);