Credit: AllWinner
The H3, A83T, and H8 variants of Linux 3.4 from AllWinner included a handy little backdoor where writing “rootmydevice” to /proc/sunxi_debug/debug would elevate your process to root. Happily, this was silently fixed with a patch that makes the feature configurable, so be on the lookout for SUN8I_ROOT_DEVICE in your ARM kernel configurations!