Linux Kernel Block Cgroup Refcount Leakage Vulnerability

A refcount leakage vulnerability has been identified in the Linux kernel's block cgroup implementation. The issue arises in the blkcg_fill_root_iostats() function, which iterates over the devices of a specified block class. This iteration is performed using class_dev_iter_(init|next)() but fails to properly terminate the iteration with class_dev_iter_exit(). As a result, the subsystem reference count for the block class is not correctly managed, leading to a leakage.

Impact

Exploitation of this vulnerability causes a subsystem reference count leakage, which can potentially lead to memory management issues.