[Qemu-devel] [PULL 7/7] qdev: Add cleanup logic in device_set_realized() to avoid resource leak

["Andreas Färber" <afaerber@suse.de>]

From: Gonglei <arei.gonglei@huawei.com>

At present, this function doesn't have partial cleanup implemented,
which will cause resource leaks in some scenarios.

Example:

1. Assume that "dc->realize(dev, &local_err)" executes successful
   and local_err == NULL;
2. device hotplug in hotplug_handler_plug() executes but fails
   (it is prone to occur). Then local_err != NULL;
3. error_propagate(errp, local_err) and return. But the resources
   which have been allocated in dc->realize() will be leaked.
Simple backtrace:
  dc->realize()
   |->device_realize
            |->pci_qdev_init()
                |->do_pci_register_device()
                |->etc.

Add fuller cleanup logic which assures that function can
goto appropriate error label as local_err population is
detected at each relevant point.

Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Peter Crosthwaite <peter.crosthwaite@xilinx.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
---
 hw/core/qdev.c | 52 ++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 38 insertions(+), 14 deletions(-)

diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 6f37cd3..fcb1638 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -834,12 +834,14 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
             dc->realize(dev, &local_err);
         }
 
-        if (dev->parent_bus && dev->parent_bus->hotplug_handler &&
-            local_err == NULL) {
+        if (local_err != NULL) {
+            goto fail;
+        }
+
+        if (dev->parent_bus && dev->parent_bus->hotplug_handler) {
             hotplug_handler_plug(dev->parent_bus->hotplug_handler,
                                  dev, &local_err);
-        } else if (local_err == NULL &&
-                   object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
+        } else if (object_dynamic_cast(qdev_get_machine(), TYPE_MACHINE)) {
             HotplugHandler *hotplug_ctrl;
             MachineState *machine = MACHINE(qdev_get_machine());
             MachineClass *mc = MACHINE_GET_CLASS(machine);
@@ -852,21 +854,24 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
             }
         }
 
-        if (qdev_get_vmsd(dev) && local_err == NULL) {
+        if (local_err != NULL) {
+            goto post_realize_fail;
+        }
+
+        if (qdev_get_vmsd(dev)) {
             vmstate_register_with_alias_id(dev, -1, qdev_get_vmsd(dev), dev,
                                            dev->instance_id_alias,
                                            dev->alias_required_for_version);
         }
-        if (local_err == NULL) {
-            QLIST_FOREACH(bus, &dev->child_bus, sibling) {
-                object_property_set_bool(OBJECT(bus), true, "realized",
+
+        QLIST_FOREACH(bus, &dev->child_bus, sibling) {
+            object_property_set_bool(OBJECT(bus), true, "realized",
                                          &local_err);
-                if (local_err != NULL) {
-                    break;
-                }
+            if (local_err != NULL) {
+                goto child_realize_fail;
             }
         }
-        if (dev->hotplugged && local_err == NULL) {
+        if (dev->hotplugged) {
             device_reset(dev);
         }
         dev->pending_deleted_event = false;
@@ -888,11 +893,30 @@ static void device_set_realized(Object *obj, bool value, Error **errp)
     }
 
     if (local_err != NULL) {
-        error_propagate(errp, local_err);
-        return;
+        goto fail;
     }
 
     dev->realized = value;
+    return;
+
+child_realize_fail:
+    QLIST_FOREACH(bus, &dev->child_bus, sibling) {
+        object_property_set_bool(OBJECT(bus), false, "realized",
+                                 NULL);
+    }
+
+    if (qdev_get_vmsd(dev)) {
+        vmstate_unregister(dev, qdev_get_vmsd(dev), dev);
+    }
+
+post_realize_fail:
+    if (dc->unrealize) {
+        dc->unrealize(dev, NULL);
+    }
+
+fail:
+    error_propagate(errp, local_err);
+    return;
 }
 
 static bool device_get_hotpluggable(Object *obj, Error **errp)
-- 
1.8.4.5