[Qemu-devel] [PATCH v2] spapr_pci: Fix potential NULL pointer dereference in spapr_dt_pci_bus()

[Philippe Mathieu-Daudé]

Commit 14e714900f6 refactored the call to spapr_dt_drc(),
introducing a potential NULL pointer dereference while
accessing bus->parent_dev.
A trivial audit show 'bus' is not null in the two places
the static function spapr_dt_drc() is called.

Since the 'bus' parameter is not NULL in both callers, remove
remove the test on if (bus), and add an assert() to silent
static analyzers.

This fixes:

  /hw/ppc/spapr_pci.c: 1367 in spapr_dt_pci_bus()
  >>>     CID 1401933:  Null pointer dereferences  (FORWARD_NULL)
  >>>     Dereferencing null pointer "bus".
  1367         ret = spapr_dt_drc(fdt, offset, OBJECT(bus->parent_dev),
  1368                            SPAPR_DR_CONNECTOR_TYPE_PCI);

Fixes: 14e714900f6
Reported-by: Coverity (CID 1401933)
Suggested-by: Greg Kurz <address@hidden>
Suggested-by: David Gibson <address@hidden>
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 hw/ppc/spapr_pci.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 957ae88bbd..fbeb1c90ee 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1356,12 +1356,11 @@ static int spapr_dt_pci_bus(SpaprPhbState *sphb, PCIBus 
*bus,
     _FDT(fdt_setprop_cell(fdt, offset, "#size-cells",
                           RESOURCE_CELLS_SIZE));
 
-    if (bus) {
-        pci_for_each_device_reverse(bus, pci_bus_num(bus),
-                                    spapr_dt_pci_device_cb, &cbinfo);
-        if (cbinfo.err) {
-            return cbinfo.err;
-        }
+    assert(bus);
+    pci_for_each_device_reverse(bus, pci_bus_num(bus),
+                                spapr_dt_pci_device_cb, &cbinfo);
+    if (cbinfo.err) {
+        return cbinfo.err;
     }
 
     ret = spapr_dt_drc(fdt, offset, OBJECT(bus->parent_dev),
-- 
2.20.1