Prevent crash due to giving QWidget::update() a large rect.

We can simply clip the update rect against the widget's rect and return
if it's empty. Otherwise we risk ending up with update rects that are
larger than INT_MAX due to multiple update rects being merged.

Task-number: QTBUG-30876
Change-Id: I23bd0149fbe8d1a007a60b228e6bddb45dc4fc32
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>
(cherry picked from commit a298216bb4383dbe96688dfb80da0cd875766de0)

1 files changed, 9 insertions, 4 deletions

diff --git a/src/gui/kernel/qwidget.cpp b/src/gui/kernel/qwidget.cpp
index b2ffac712a..481f3235d6 100644
--- a/src/gui/kernel/qwidget.cpp
+++ b/src/gui/kernel/qwidget.cpp
@@ -10561,11 +10561,16 @@ void QWidget::update()
 */
 void QWidget::update(const QRect &rect)
 {
-    if (!isVisible() || !updatesEnabled() || rect.isEmpty())
+    if (!isVisible() || !updatesEnabled())
+        return;
+
+    QRect r = rect & QWidget::rect();
+
+    if (r.isEmpty())
         return;
 
     if (testAttribute(Qt::WA_WState_InPaintEvent)) {
-        QApplication::postEvent(this, new QUpdateLaterEvent(rect));
+        QApplication::postEvent(this, new QUpdateLaterEvent(r));
         return;
     }
 
@@ -10578,9 +10583,9 @@ void QWidget::update(const QRect &rect)
 #endif // QT_MAC_USE_COCOA
         QTLWExtra *tlwExtra = window()->d_func()->maybeTopData();
         if (tlwExtra && !tlwExtra->inTopLevelResize && tlwExtra->backingStore)
-            tlwExtra->backingStore->markDirty(rect, this);
+            tlwExtra->backingStore->markDirty(r, this);
     } else {
-        d_func()->repaint_sys(rect);
+        d_func()->repaint_sys(r);
     }
 }