QPixmap::loadFromData crashes on invalid data on X11,
here is the simple example which reproduces the bug:

#include <QtGui>

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

QByteArray data("some incorrect image data");

QPixmap pixmap;
pixmap.loadFromData(data);

return 0;
}

Backtrace:

#0 0xb75ff40b in QImageData::checkForAlphaPixels (this=0x0) at depot/qt/qt/src/gui/image/qimage.cpp:273
#1 0xb764e9c7 in QX11AlphaDetector::hasAlpha (this=0xbff60b28) at depot/qt/qt/src/gui/image/qpixmap_x11.cpp:385
#2 0xb764ea1a in QX11AlphaDetector::hasXRenderAndAlpha (this=0xbff60b28) at depot/qt/qt/src/gui/image/qpixmap_x11.cpp:392
#3 0xb764665d in QX11PixmapData::fromImage (this=0x8088ec0, img=@0xbff60f5c, flags=

{i = -1074393256}

)
at depot/qt/qt/src/gui/image/qpixmap_x11.cpp:443
#4 0xb76371e2 in QPixmapData::fromData (this=0x8088ec0, buf=0x80716a8 "some incorrect image data", len=25, format=0x0, flags=

{i = -1074393176}

)
at depot/qt/qt/src/gui/image/qpixmapdata.cpp:132
#5 0xb762d365 in QPixmap::loadFromData (this=0xbff61010, buf=0x80716a8 "some incorrect image data", len=25, format=0x0, flags=

{i = -1074393120}

)
at depot/qt/qt/src/gui/image/qpixmap.cpp:872
#6 0x08048a12 in QPixmap::loadFromData (this=0xbff61010, buf=@0xbff6101c, format=0x0, flags=

{i = -1074393048}

)
at depot/qt/qt/src/gui/image/qpixmap.h:302
#7 0x080488c7 in main (argc=0, argv=0xb8035ff4) at testpixmap/main.cpp:10