Comment 7 for bug 1351376

Well, here's the comment in the upstream bug report where the developer says it's fixed:
https://www.virtualbox.org/ticket/12941#comment:36

As he said,
> the commit message will be: "Additions/x11/vboxvideo: properly report the file descriptor for the kernel driver to allow authentication to work."

So, looking at the github mirror (which is much more convenient than the upstream repo interface), I found that commit quite quickly:
https://github.com/mdaniel/virtualbox-org-svn-vbox-trunk/commit/091213fd0b5e319918172d1f486cdf2bfffb75ff

I can't test it at the moment, but I'll get back to it later and check if it's applicable to 4.3.10 source (because the commit is from 4.3.13).