Avoid creating wide images with negative bytesPerLine

The QImage API can not handle images with more bytes per line than what
an integer can hold.

Fixes: QTBUG-73731
Fixes: QTBUG-73732
Change-Id: Ieed6fec7645661fd58d8d25335f806faaa1bb3e9
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

4 files changed, 39 insertions, 2 deletions

diff --git a/src/gui/image/qimage.cpp b/src/gui/image/qimage.cpp
index 9897c3aa6f..3e18ca6528 100644
--- a/src/gui/image/qimage.cpp
+++ b/src/gui/image/qimage.cpp
@@ -124,7 +124,7 @@ QImageData * QImageData::create(const QSize &size, QImage::Format format)
     int height = size.height();
     int depth = qt_depthForFormat(format);
     auto params = calculateImageParameters(width, height, depth);
-    if (params.bytesPerLine < 0)
+    if (!params.isValid())
         return nullptr;
 
     QScopedPointer<QImageData> d(new QImageData);
@@ -781,7 +781,7 @@ QImageData *QImageData::create(uchar *data, int width, int height,  int bpl, QIm
 
     const int depth = qt_depthForFormat(format);
     auto params = calculateImageParameters(width, height, depth);
-    if (params.totalSize < 0)
+    if (!params.isValid())
         return nullptr;
 
     if (bpl > 0) {
@@ -1484,10 +1484,17 @@ qsizetype QImage::sizeInBytes() const
 
     \sa scanLine()
 */
+#if QT_VERSION >= QT_VERSION_CHECK(6,0,0)
+qsizetype QImage::bytesPerLine() const
+{
+    return d ? d->bytes_per_line : 0;
+}
+#else
 int QImage::bytesPerLine() const
 {
     return d ? d->bytes_per_line : 0;
 }
+#endif
 
 
 /*!
diff --git a/src/gui/image/qimage.h b/src/gui/image/qimage.h
index 4b7a3b1ead..6505fd5845 100644
--- a/src/gui/image/qimage.h
+++ b/src/gui/image/qimage.h
@@ -227,7 +227,11 @@ public:
     uchar *scanLine(int);
     const uchar *scanLine(int) const;
     const uchar *constScanLine(int) const;
+#if QT_VERSION >= QT_VERSION_CHECK(6,0,0)
+    qsizetype bytesPerLine() const;
+#else
     int bytesPerLine() const;
+#endif
 
     bool valid(int x, int y) const;
     bool valid(const QPoint &pt) const;
diff --git a/src/gui/image/qimage_p.h b/src/gui/image/qimage_p.h
index e3a6c53833..a0a3b5406e 100644
--- a/src/gui/image/qimage_p.h
+++ b/src/gui/image/qimage_p.h
@@ -109,6 +109,7 @@ struct Q_GUI_EXPORT QImageData {        // internal image data
     struct ImageSizeParameters {
         qsizetype bytesPerLine;
         qsizetype totalSize;
+        bool isValid() const { return bytesPerLine > 0 && totalSize > 0; }
     };
     static ImageSizeParameters calculateImageParameters(qsizetype width, qsizetype height, qsizetype depth);
 };
@@ -135,6 +136,11 @@ QImageData::calculateImageParameters(qsizetype width, qsizetype height, qsizetyp
     qsizetype dummy;
     if (mul_overflow(height, qsizetype(sizeof(uchar *)), &dummy))
         return invalid;                                 // why is this here?
+#if QT_VERSION < QT_VERSION_CHECK(6,0,0)
+    // Disallow images where width * depth calculations might overflow
+    if (width > (INT_MAX - 31) / depth)
+        return invalid;
+#endif
 
     return { bytes_per_line, total_size };
 }
diff --git a/tests/auto/gui/image/qimage/tst_qimage.cpp b/tests/auto/gui/image/qimage/tst_qimage.cpp
index eded206d37..6bc27a6e16 100644
--- a/tests/auto/gui/image/qimage/tst_qimage.cpp
+++ b/tests/auto/gui/image/qimage/tst_qimage.cpp
@@ -230,6 +230,8 @@ private slots:
 
     void convertColorTable();
 
+    void wideImage();
+
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
     void toWinHBITMAP_data();
     void toWinHBITMAP();
@@ -3535,6 +3537,24 @@ void tst_QImage::convertColorTable()
     QCOMPARE(rgb32.pixel(0,0), 0xffffffff);
 }
 
+void tst_QImage::wideImage()
+{
+    // QTBUG-73731 and QTBUG-73732
+    QImage i(538994187, 2, QImage::Format_ARGB32);
+    QImage i2(32, 32, QImage::Format_ARGB32);
+    i2.fill(Qt::white);
+
+    // Test that it doesn't crash:
+    QPainter painter(&i);
+    // With the composition mode is SourceOver out it's an invalid write
+    // With the composition mode is Source it's an invalid read
+    painter.drawImage(0, 0, i2);
+    painter.setCompositionMode(QPainter::CompositionMode_Source);
+    painter.drawImage(0, 0, i2);
+
+    // Qt6: Test that it actually works on 64bit architectures.
+}
+
 #if defined(Q_OS_WIN) && !defined(Q_OS_WINRT)
 QT_BEGIN_NAMESPACE
 Q_GUI_EXPORT HBITMAP qt_imageToWinHBITMAP(const QImage &p, int hbitmapFormat = 0);