5 files changed, 29 insertions, 9 deletions
diff --git a/src/corelib/compat/removed_api.cpp b/src/corelib/compat/removed_api.cpp
index c8cc969f819..24699355ec4 100644
--- a/src/corelib/compat/removed_api.cpp
+++ b/src/corelib/compat/removed_api.cpp
@@ -1012,11 +1012,13 @@ int QObject::startTimer(std::chrono::milliseconds time, Qt::TimerType timerType)
 {
     using namespace std::chrono;
     using ratio = std::ratio_divide<std::milli, std::nano>;
-    if (nanoseconds::rep r; qMulOverflow<ratio::num>(time.count(), &r)) {
-        qWarning("QObject::startTimer(std::chrono::milliseconds time ...): "
-                 "'time' arg will overflow when converted to nanoseconds.");
+    nanoseconds::rep r;
+    if (qMulOverflow<ratio::num>(time.count(), &r)) {
+        qWarning("QObject::startTimer(std::chrono::milliseconds): "
+                 "'time' arg overflowed when converted to nanoseconds.");
+        r = nanoseconds::max().count();
     }
-    return startTimer(nanoseconds{time}, timerType);
+    return startTimer(nanoseconds{r}, timerType);
 }
 
 #if QT_CONFIG(processenvironment)
diff --git a/src/corelib/kernel/qobject.cpp b/src/corelib/kernel/qobject.cpp
index 708b10a75ee..e1129c5d251 100644
--- a/src/corelib/kernel/qobject.cpp
+++ b/src/corelib/kernel/qobject.cpp
@@ -1816,6 +1816,8 @@ void QObjectPrivate::setThreadData_helper(QThreadData *currentData, QThreadData
 
 int QObject::startTimer(int interval, Qt::TimerType timerType)
 {
+    // no overflow can happen here:
+    // 2^31 ms * 1,000,000 always fits a 64-bit signed integer type
     return startTimer(std::chrono::milliseconds{interval}, timerType);
 }
 
diff --git a/src/corelib/kernel/qsingleshottimer_p.h b/src/corelib/kernel/qsingleshottimer_p.h
index d7e33c52212..dd1402f63a1 100644
--- a/src/corelib/kernel/qsingleshottimer_p.h
+++ b/src/corelib/kernel/qsingleshottimer_p.h
@@ -19,6 +19,7 @@
 #include "qabstracteventdispatcher.h"
 #include "qcoreapplication.h"
 #include "qmetaobject_p.h"
+#include "private/qnumeric_p.h"
 
 #include <chrono>
 
@@ -43,6 +44,20 @@ public:
     inline void startTimerForReceiver(Duration interval, Qt::TimerType timerType,
                                       const QObject *receiver);
 
+    static Duration fromMsecs(std::chrono::milliseconds ms)
+    {
+        using namespace std::chrono;
+        using ratio = std::ratio_divide<std::milli, Duration::period>;
+        static_assert(ratio::den == 1);
+
+        Duration::rep r;
+        if (qMulOverflow<ratio::num>(ms.count(), &r)) {
+            qWarning("QTimer::singleShot(std::chrono::milliseconds, ...): "
+                     "interval argument overflowed when converted to nanoseconds.");
+            return Duration::max();
+        }
+        return Duration{r};
+    }
 Q_SIGNALS:
     void timeout();
 
diff --git a/src/corelib/kernel/qtimer.cpp b/src/corelib/kernel/qtimer.cpp
index cc46c1433b5..294369c1b33 100644
--- a/src/corelib/kernel/qtimer.cpp
+++ b/src/corelib/kernel/qtimer.cpp
@@ -213,7 +213,7 @@ void QTimer::start()
     if (d->isActive()) // stop running timer
         stop();
 
-    const auto newId = Qt::TimerId{QObject::startTimer(d->inter * 1ms, d->type)};
+    Qt::TimerId newId{ QObject::startTimer(d->inter * 1ms, d->type) }; // overflow impossible
     if (newId > Qt::TimerId::Invalid) {
         d->id = newId;
         d->isActiveData.notify();
@@ -332,7 +332,7 @@ void QTimer::singleShotImpl(std::chrono::milliseconds msec, Qt::TimerType timerT
         return;
     }
 
-    new QSingleShotTimer(msec, timerType, receiver, slotObj);
+    new QSingleShotTimer(QSingleShotTimer::fromMsecs(msec), timerType, receiver, slotObj);
 }
 
 /*!
@@ -396,7 +396,7 @@ void QTimer::singleShot(std::chrono::milliseconds msec, Qt::TimerType timerType,
                                       Qt::QueuedConnection);
             return;
         }
-        (void) new QSingleShotTimer(msec, timerType, receiver, member);
+        (void) new QSingleShotTimer(QSingleShotTimer::fromMsecs(msec), timerType, receiver, member);
     }
 }
 
@@ -592,7 +592,7 @@ void QTimer::setInterval(std::chrono::milliseconds interval)
     d->inter.setValueBypassingBindings(msec);
     if (d->isActive()) { // create new timer
         QObject::killTimer(d->id);                        // restart timer
-        const auto newId = Qt::TimerId{QObject::startTimer(msec * 1ms, d->type)};
+        Qt::TimerId newId{ QObject::startTimer(msec * 1ms, d->type) };  // overflow impossible
         if (newId > Qt::TimerId::Invalid) {
             // Restarted successfully. No need to update the active state.
             d->id = newId;
diff --git a/src/dbus/qdbusintegrator.cpp b/src/dbus/qdbusintegrator.cpp
index 89b9b2d17e6..836562f496d 100644
--- a/src/dbus/qdbusintegrator.cpp
+++ b/src/dbus/qdbusintegrator.cpp
@@ -151,7 +151,8 @@ static dbus_bool_t qDBusAddTimeout(DBusTimeout *timeout, void *data)
 
     Q_ASSERT(d->timeouts.key(timeout, 0) == 0);
 
-    int timerId = d->startTimer(std::chrono::milliseconds{q_dbus_timeout_get_interval(timeout)});
+    using namespace std::chrono_literals;
+    int timerId = d->startTimer(q_dbus_timeout_get_interval(timeout) * 1ms); // no overflow possible
     if (!timerId)
         return false;