concrete real-life examples where grsecurity prevented an exploit

From theoretical point of view, grsecurity kernel patch looks like a great hardening tool. Most importantly, PaX seems like a good idea.

Do these theoretical advantages have indeed practical effect in preventing malware attack/exploits/rootkits ?

There were several critical security problems recently (Shellshock, Heartbleed, Turla, ... to name just a few)

Can somebody please point to a concrete exploit which grsecurity would have prevented ?