Memory corruption via invalid scheduler list conversion

Memory corruption in the Linux kernel scheduler allows local users to access garbage data or trigger a memory fault. In child_cfs_rq_on_list, a prev pointer that can denote rq->leaf_cfs_rq_list is incorrectly passed through container_of as though it belonged to a cfs_rq. Low-privileged local access is required, and the resulting invalid task-group pointer can corrupt memory or crash the kernel, although the published layout can mask the fault.