[Qemu-devel] [PATCH v2 3/4] console: Abort on property access errors

[Kirill Batuzov]

All defined properties of QemuConsole are mandatory and no access to them
should fail. Nevertheless not checking returned errors is bad because in case
of unexpected failure it will hide the bug and cause a memory leak.

Abort in case of unexpected property access errors. This change exposed a bug
where an attempt was made to write to a read-only property "head".

Set "head" property's value at creation time and do not attempt to change it
later. This fixes the bug mentioned above.

Signed-off-by: Kirill Batuzov <address@hidden>
---
 ui/console.c |   30 +++++++++++++-----------------
 1 file changed, 13 insertions(+), 17 deletions(-)

v1 -> v2:
 Use &error_abort instead of silently ignoring errors.
 Properly initialize property "head".

diff --git a/ui/console.c b/ui/console.c
index e057755..bc6ad99 100644
--- a/ui/console.c
+++ b/ui/console.c
@@ -1167,9 +1167,9 @@ static void text_console_update(void *opaque, 
console_ch_t *chardata)
     }
 }
 
-static QemuConsole *new_console(DisplayState *ds, console_type_t console_type)
+static QemuConsole *new_console(DisplayState *ds, console_type_t console_type,
+                                uint32_t head)
 {
-    Error *local_err = NULL;
     Object *obj;
     QemuConsole *s;
     int i;
@@ -1179,13 +1179,14 @@ static QemuConsole *new_console(DisplayState *ds, 
console_type_t console_type)
 
     obj = object_new(TYPE_QEMU_CONSOLE);
     s = QEMU_CONSOLE(obj);
+    s->head = head;
     object_property_add_link(obj, "device", TYPE_DEVICE,
                              (Object **)&s->device,
                              object_property_allow_set_link,
                              OBJ_PROP_LINK_UNREF_ON_RELEASE,
-                             &local_err);
+                             &error_abort);
     object_property_add_uint32_ptr(obj, "head",
-                                   &s->head, &local_err);
+                                   &s->head, &error_abort);
 
     if (!active_console || ((active_console->console_type != GRAPHIC_CONSOLE) 
&&
         (console_type == GRAPHIC_CONSOLE))) {
@@ -1560,7 +1561,6 @@ static DisplayState *get_alloc_displaystate(void)
  */
 DisplayState *init_displaystate(void)
 {
-    Error *local_err = NULL;
     gchar *name;
     int i;
 
@@ -1579,7 +1579,7 @@ DisplayState *init_displaystate(void)
          * doesn't change any more */
         name = g_strdup_printf("console[%d]", i);
         object_property_add_child(container_get(object_get_root(), "/backend"),
-                                  name, OBJECT(consoles[i]), &local_err);
+                                  name, OBJECT(consoles[i]), &error_abort);
         g_free(name);
     }
 
@@ -1590,7 +1590,6 @@ QemuConsole *graphic_console_init(DeviceState *dev, 
uint32_t head,
                                   const GraphicHwOps *hw_ops,
                                   void *opaque)
 {
-    Error *local_err = NULL;
     int width = 640;
     int height = 480;
     QemuConsole *s;
@@ -1598,14 +1597,12 @@ QemuConsole *graphic_console_init(DeviceState *dev, 
uint32_t head,
 
     ds = get_alloc_displaystate();
     trace_console_gfx_new();
-    s = new_console(ds, GRAPHIC_CONSOLE);
+    s = new_console(ds, GRAPHIC_CONSOLE, head);
     s->hw_ops = hw_ops;
     s->hw = opaque;
     if (dev) {
-        object_property_set_link(OBJECT(s), OBJECT(dev),
-                                 "device", &local_err);
-        object_property_set_int(OBJECT(s), head,
-                                "head", &local_err);
+        object_property_set_link(OBJECT(s), OBJECT(dev), "device",
+                                 &error_abort);
     }
 
     s->surface = qemu_create_displaysurface(width, height);
@@ -1622,7 +1619,6 @@ QemuConsole *qemu_console_lookup_by_index(unsigned int 
index)
 
 QemuConsole *qemu_console_lookup_by_device(DeviceState *dev, uint32_t head)
 {
-    Error *local_err = NULL;
     Object *obj;
     uint32_t h;
     int i;
@@ -1632,12 +1628,12 @@ QemuConsole *qemu_console_lookup_by_device(DeviceState 
*dev, uint32_t head)
             continue;
         }
         obj = object_property_get_link(OBJECT(consoles[i]),
-                                       "device", &local_err);
+                                       "device", &error_abort);
         if (DEVICE(obj) != dev) {
             continue;
         }
         h = object_property_get_int(OBJECT(consoles[i]),
-                                    "head", &local_err);
+                                    "head", &error_abort);
         if (h != head) {
             continue;
         }
@@ -1811,9 +1807,9 @@ static CharDriverState *text_console_init(ChardevVC *vc)
 
     trace_console_txt_new(width, height);
     if (width == 0 || height == 0) {
-        s = new_console(NULL, TEXT_CONSOLE);
+        s = new_console(NULL, TEXT_CONSOLE, 0);
     } else {
-        s = new_console(NULL, TEXT_CONSOLE_FIXED_SIZE);
+        s = new_console(NULL, TEXT_CONSOLE_FIXED_SIZE, 0);
         s->surface = qemu_create_displaysurface(width, height);
     }
 
-- 
1.7.10.4