[Qemu-ppc] [PATCH] spapr_pci: fix potential NULL pointer dereference

[Greg Kurz]

Commit 2c88b098e76fd added a call to SPAPR_MACHINE_GET_CLASS(spapr) in
spapr_phb_realize() before we check spapr isn't NULL. This causes QEMU
to crash when starting a non-pseries machine with a sPAPR PHB.

This could be fixed by setting the smc variable after the null check,
but it seems more explicit to use a ternary operator to skip the call
to SPAPR_MACHINE_GET_CLASS() if spapr is NULL, since spapr_phb_realize()
will return immediately in this case.

This was reported by Coverity (CID 1395170 and 1395183).

Fixes: 2c88b098e76fde0c7fcc0476dd3f80ce58409505
Signed-off-by: Greg Kurz <address@hidden>
---
 hw/ppc/spapr_pci.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
index 5cd676e4430d..6bcb4f419b6b 100644
--- a/hw/ppc/spapr_pci.c
+++ b/hw/ppc/spapr_pci.c
@@ -1559,7 +1559,7 @@ static void spapr_phb_realize(DeviceState *dev, Error 
**errp)
     sPAPRMachineState *spapr =
         (sPAPRMachineState *) object_dynamic_cast(qdev_get_machine(),
                                                   TYPE_SPAPR_MACHINE);
-    sPAPRMachineClass *smc = SPAPR_MACHINE_GET_CLASS(spapr);
+    sPAPRMachineClass *smc = spapr ? SPAPR_MACHINE_GET_CLASS(spapr) : NULL;
     SysBusDevice *s = SYS_BUS_DEVICE(dev);
     sPAPRPHBState *sphb = SPAPR_PCI_HOST_BRIDGE(s);
     PCIHostState *phb = PCI_HOST_BRIDGE(s);