QImage::fromData() infinite loop on an image that can be loaded with QImage( path)

#include <QtGui/QApplication>
#include <QPixmap>
#include <QImage>
#include <QLabel>
#include <QFile>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);

    QString pathToImage = "image_1404.jpg";

//   This loads the image successfully
    QImage img( pathToImage);
    QLabel l;
    l.setPixmap( QPixmap::fromImage( img)); 
    l.show();

//  This will infinite-loop in jdmarker.c
    QFile f( pathToImage);
    if( f.open( QIODevice::ReadOnly))
    {
        QByteArray a = f.readAll();
        img = QImage::fromData( a);
    }

    QLabel l2;
    l2.setPixmap( QPixmap::fromImage( img));
    l2.show();

    return a.exec();
}