hmp: do not crash on invalid SCSI hotplug

Commit 0d93692 (qdev: Convert busses to QEMU Object Model, 2012-05-02)
removed a check on the type of the bus where a SCSI disk is hotplugged.
However, hot-plugging to the wrong kind of device now causes a crash
due to either a NULL pointer dereference (avoided by the previous patch)
or a failed QOM cast.

Instead, in this case we need to use object_dynamic_cast and check for
the result, similar to what was done before that commit.

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
index e7fb780a088280b085e742c7547d056cbf167998..0ca5546fc6be75d58d28bb1251a90e38eb1b6e59 100644 (file)
--- a/hw/pci-hotplug.c
+++ b/hw/pci-hotplug.c
@@ -80,7 +80,13 @@ static int scsi_hot_add(Monitor *mon, DeviceState *adapter,
     SCSIBus *scsibus;
     SCSIDevice *scsidev;
 
-    scsibus = SCSI_BUS(QLIST_FIRST(&adapter->child_bus));
+    scsibus = (SCSIBus *)
+        object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
+                            TYPE_SCSI_BUS);
+    if (!scsibus) {
+       error_report("Device is not a SCSI adapter");
+       return -1;
+    }
 
     /*
      * drive_init() tries to find a default for dinfo->unit.  Doesn't