Dump ram on ros?

I exploited a wap60g and downloaded a busybox. If I try

dd if=/dev/mem ...

it says

dd: /dev/mem: Bad address

How else, can you dump the ram on ros?

They disabled both kmem and mem so you cant use that.
You cant dump RAM with anyhting, I wasted a month on trying to do it on ROS.
They are using ancient version of kernel and it will always return an impossible address as the end of RAM so LiMe will crash.