4 files changed, 15 insertions, 9 deletions
diff --git a/src/gui/image/qpicture.cpp b/src/gui/image/qpicture.cpp
index 6e57f679d8..56b82abcfa 100644
--- a/src/gui/image/qpicture.cpp
+++ b/src/gui/image/qpicture.cpp
@@ -1866,7 +1866,7 @@ QList<QByteArray> QPictureIO::outputFormats()
 bool QPictureIO::read()
 {
     QFile           file;
-    const char          *picture_format;
+    QByteArray      picture_format;
     QPictureHandler *h;
 
     if (d->iodev) {                                // read from io device
@@ -1882,7 +1882,7 @@ bool QPictureIO::read()
     if (d->frmt.isEmpty()) {
         // Try to guess format
         picture_format = pictureFormat(d->iodev);        // get picture format
-        if (!picture_format) {
+        if (picture_format.isEmpty()) {
             if (file.isOpen()) {                        // unknown format
                 file.close();
                 d->iodev = 0;
diff --git a/src/gui/image/qpixmap.cpp b/src/gui/image/qpixmap.cpp
index 1ec4e3488a..2ef1d09422 100644
--- a/src/gui/image/qpixmap.cpp
+++ b/src/gui/image/qpixmap.cpp
@@ -714,8 +714,8 @@ QBitmap QPixmap::createMaskFromColor(const QColor &maskColor, Qt::MaskMode mode)
     control the conversion.
 
     Note that QPixmaps are automatically added to the QPixmapCache
-    when loaded from a file; the key used is internal and can not
-    be acquired.
+    when loaded from a file in main thread; the key used is internal
+    and cannot be acquired.
 
     \sa loadFromData(), {QPixmap#Reading and Writing Image
     Files}{Reading and Writing Image Files}
@@ -729,6 +729,7 @@ bool QPixmap::load(const QString &fileName, const char *format, Qt::ImageConvers
         // Note: If no extension is provided, we try to match the
         // file against known plugin extensions
         if (info.completeSuffix().isEmpty() || info.exists()) {
+            const bool inGuiThread = qApp->thread() == QThread::currentThread();
 
             QString key = QLatin1String("qt_pixmap")
                     % info.absoluteFilePath()
@@ -736,13 +737,14 @@ bool QPixmap::load(const QString &fileName, const char *format, Qt::ImageConvers
                     % HexString<quint64>(info.size())
                     % HexString<uint>(data ? data->pixelType() : QPlatformPixmap::PixmapType);
 
-            if (QPixmapCache::find(key, this))
+            if (inGuiThread && QPixmapCache::find(key, this))
                 return true;
 
             data = QPlatformPixmap::create(0, 0, data ? data->pixelType() : QPlatformPixmap::PixmapType);
 
             if (data->fromFile(fileName, format, flags)) {
-                QPixmapCache::insert(key, *this);
+                if (inGuiThread)
+                    QPixmapCache::insert(key, *this);
                 return true;
             }
         }
diff --git a/src/gui/image/qpnghandler.cpp b/src/gui/image/qpnghandler.cpp
index 3655c39326..1a5e7718eb 100644
--- a/src/gui/image/qpnghandler.cpp
+++ b/src/gui/image/qpnghandler.cpp
@@ -233,8 +233,8 @@ void setup_qt(QImage& image, png_structp png_ptr, png_infop info_ptr, QSize scal
 
     png_uint_32 width;
     png_uint_32 height;
-    int bit_depth;
-    int color_type;
+    int bit_depth = 0;
+    int color_type = 0;
     png_bytep trans_alpha = 0;
     png_color_16p trans_color_p = 0;
     int num_trans;
@@ -690,7 +690,7 @@ QImage::Format QPngHandlerPrivate::readImageFormat()
 {
         QImage::Format format = QImage::Format_Invalid;
         png_uint_32 width, height;
-        int bit_depth, color_type;
+        int bit_depth = 0, color_type = 0;
         png_colorp palette;
         int num_palette;
         png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, 0, 0, 0);
diff --git a/src/gui/image/qxbmhandler.cpp b/src/gui/image/qxbmhandler.cpp
index 24d86e116d..7ba44049b4 100644
--- a/src/gui/image/qxbmhandler.cpp
+++ b/src/gui/image/qxbmhandler.cpp
@@ -97,6 +97,8 @@ static bool read_xbm_header(QIODevice *device, int& w, int& h)
     if (r1.indexIn(sbuf) == 0 &&
          r2.indexIn(sbuf, r1.matchedLength()) == r1.matchedLength())
         w = QByteArray(&buf[r1.matchedLength()]).trimmed().toInt();
+    else
+        return false;
 
     // "#define .._height <num>"
     readBytes = device->readLine(buf, buflen);
@@ -109,6 +111,8 @@ static bool read_xbm_header(QIODevice *device, int& w, int& h)
     if (r1.indexIn(sbuf) == 0 &&
          r2.indexIn(sbuf, r1.matchedLength()) == r1.matchedLength())
         h = QByteArray(&buf[r1.matchedLength()]).trimmed().toInt();
+    else
+        return false;
 
     // format error
     if (w <= 0 || w > 32767 || h <= 0 || h > 32767)