The thing is that according to RedHat the attacker has to be a local user, which implies that you know the local user, with unprivileged access. It does not say whether that user is allowed to execute code loaded from an external source, e.g. USB memory stick...
As I am not a professional I must assume that standard users are NOT allowed only admin' staff.
CVE-2016-5195 - Red Hat Customer Portal
However, and to me this is a big however, the Rowhammer _bug_ is much more serious as it can be buried inside a """free""" app' that could be DLed from so-called reputable sources and be stealthily called or installed inside what looks like a _cool_ app'. NASTY!
As we all know race conditions occur all the time in both HW and/or SW.
I had the condition(s) on both the AMIGA1200 and PC parallel ports when accessing HW I built many years ago so I am aware of situations like this. Obviously these were not OS crippling events but they taught me a lot and to research more about the situation.
Current technology is frighteningly quick compared to those units of yesteryear so even nanoseconds can be the breakpoint of today's HW...
I can't find any test code for Rowhammer though to see how it works... ;o(
...But I could guess though and probably be close enough without any said test code.