In the Linux kernel, the following vulnerability has been resolved: netsched: Prevent creation of classes with TCHROOT The function qdisctreereducebacklog() uses TCHROOT as a termination condition when traversing up the qdisc tree to update parent backlog counters. However, if a class is created with classid TCHROOT, the traversal terminates prematurely at this class instead of reaching the actual root qdisc, causing parent statistics to be incorrectly maintained. In case of DRR, this could lead to a crash as reported by Mingi Cho. Prevent the creation of any Qdisc class with classid TCHROOT (0xFFFFFFFF) across all qdisc types, as suggested by Jamal.