It looks like these fixes are needed for 4.19 (and older stable branches):
commit 2507e6ab7a9a440773be476141a255934468c5ef Author: Navid Emamdoost navid.emamdoost@gmail.com Date: Tue Sep 10 18:01:40 2019 -0500
wimax: i2400: fix memory leak
commit 6f3ef5c25cc762687a7341c18cbea5af54461407 Author: Navid Emamdoost navid.emamdoost@gmail.com Date: Fri Oct 25 23:53:30 2019 -0500
wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle
Ben.