vbox-kernel-module-src-4.20 consists of 4.1.22 version, so the module is not adequate to virtualbox-4.20
What package is that?
*** Bug 434950 has been marked as a duplicate of this bug. ***
+*virtualbox-modules-4.2.0-r1 (14 Sep 2012) + + 14 Sep 2012; Lars Wendler <polynomial-c@gentoo.org> + -virtualbox-modules-4.2.0.ebuild, +virtualbox-modules-4.2.0-r1.ebuild: + Fixed 4.2.0 tarball (4.1.22 ersion was mistakenly packaged as 4.2.0 version). + This fixes bug #434958. This was really stupid from me. I have no idea what happened that I used the wrong sources when creating the tarball. Sorry for all the inconveniences.
*** Bug 434974 has been marked as a duplicate of this bug. ***
*** Bug 434980 has been marked as a duplicate of this bug. ***