Linux Kernel Memory Cgroup Reference Leak Vulnerability in DAMON Sysfs Schemes

A vulnerability in the Linux kernel's memory management subsystem, specifically within the DAMON (Data Access Monitor) framework, has been addressed. The issue arose because the function 'damon_sysfs_memcg_path_to_id()'' improperly exited a loop iterating over memory cgroups without calling 'mem_cgroup_iter_break()'. This oversight led to a leak of the cgroup reference. The vulnerability affects the Linux kernel stable tree, particularly versions 6.3.x. The problem has been fixed by ensuring 'mem_cgroup_iter_break()' is called before exiting the loop, thereby preventing the reference leak.

Impact

The vulnerability could lead to a memory leak by not properly releasing references to memory cgroups, potentially causing increased memory usage over time.

Reproduction

The vulnerability can be reproduced by using the DAMON sysfs schemes feature in the Linux kernel. When the 'damon_sysfs_memcg_path_to_id()' function is called, it will break the 'mem_cgroup_iter()' loop without properly calling 'mem_cgroup_iter_break()'. This sequence of actions will result in a leak of the cgroup reference, demonstrating the vulnerability.

Remediation

Users can upgrade to the patched version of the Linux kernel available in the Linux Kernel Git Repository under the stable branch. The specific commit addressing this vulnerability is '082351f9d40007414ad6af062b3a26fa02fd4b5f', which can be downloaded as a tarball.