Improve checking for event/socket notifiers and timers

Starting/stopping timers from another thread may result in errors that
may not appear until hours, days or weeks after if a release build of
Qt is used with the GLib/UNIX event dispatchers. Such errors may
manifest as warnings such as "QObject::killTimer(): Error: timer id 7
is not valid for object 0x2a51b488 (), timer has not been killed" and
application crashes (e.g. crashes in malloc, realloc and
malloc_consolidate).

Initial-patch-by: Eike Ziller <eike.ziller@digia.com>
Task-number: QTBUG-40636
Change-Id: I2de50d50eb1fc7467fcebb9c73b74d2f85137933
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/corelib/kernel/qsocketnotifier.cpp b/src/corelib/kernel/qsocketnotifier.cpp
index 6470873d9a..2598f02a19 100644
--- a/src/corelib/kernel/qsocketnotifier.cpp
+++ b/src/corelib/kernel/qsocketnotifier.cpp
@@ -274,6 +274,10 @@ void QSocketNotifier::setEnabled(bool enable)
 
     if (!d->threadData->eventDispatcher.load()) // perhaps application/thread is shutting down
         return;
+    if (Q_UNLIKELY(thread() != QThread::currentThread())) {
+        qWarning("QSocketNotifier: Socket notifiers cannot be enabled or disabled from another thread");
+        return;
+    }
     if (d->snenabled)
         d->threadData->eventDispatcher.load()->registerSocketNotifier(this);
     else