I want to make a half wall beside a staircase (on the edge of the upper floor). One end will be attached to a concrete column, but the other will be (so far) unsuported. Something like the picture below:

What is the best way to ensure that It stays put and strong? If nothing else I will make a square tubing post (100x100mm, 1.5mm thick) from floor to ceiling and attach the drywall to it.

Any other ideas?

EDIT: No wood studs in Brazil, actually it is very hard to get good construction lumber around (most aren't dry, and pressure treated is rare and expensive as hell).