Bug#849479: tigervnc: CVE-2014-8240: integer overflow flaw, leading to a heap-based buffer overflow in screen size handling

[Salvatore Bonaccorso]

Example, we have the following code in Image.cxx (all Debian patches
applied):

 75 void Image::Init(int width, int height)                                     
                  
 76 {
 77   Visual* vis = DefaultVisual(dpy, DefaultScreen(dpy));
 78   trueColor = (vis->c_class == TrueColor);
 79 
 80   xim = XCreateImage(dpy, vis, DefaultDepth(dpy, DefaultScreen(dpy)),
 81                      ZPixmap, 0, 0, width, height, BitmapPad(dpy), 0);
 82 
 83   xim->data = (char *)malloc(xim->bytes_per_line * xim->height);

The referenced Red Hat patch will first validate xim->byptes_per_line
et al.

Regards,
Salvatore