{"id":"CVE-2023-54107","title":"blk-cgroup: dropping parent refcount after pd_free_fn() is done","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_f…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= d578c770c85233af592e54537f93f3831bde7e9a < c7241babf0855d8a6180cd1743ff0ec34de40b4e","Linux 5.18"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-15T21:38:32.237187Z"},"published":"2025-12-24","updated":"2026-10-15","sourceUpdated":"2026-10-15T21:41:39.921Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2023-54107","references":[{"url":"https://git.kernel.org/stable/c/c7241babf0855d8a6180cd1743ff0ec34de40b4e"}],"tags":["cve.org"],"epss":0.00152,"epssPercentile":0.03896,"ingestedAt":"2026-10-15T22:48:25.429Z","slug":"CVE-2023-54107","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: dropping parent refcount after pd_free_fn() is done\n\nSome cgroup policies will access parent pd through child pd even\nafter pd_offline_fn() is done. If pd_free_fn() for parent is called\nbefore child, then UAF can be triggered. Hence it's better to guarantee\nthe order of pd_free_fn().\n\nCurrently refcount of parent blkg is dropped in __blkg_release(), which\nis before pd_free_fn() is called in blkg_free_work_fn() while\nblkg_free_work_fn() is called asynchronously.\n\nThis patch make sure pd_free_fn() called from removing cgroup is ordered\nby delaying dropping parent refcount after calling pd_free_fn() for\nchild.\n\nBTW, pd_free_fn() will also be called from blkcg_deactivate_policy()\nfrom deleting device, and following patches will guarantee the order.\n\n## Affected\n\n- `Linux >= d578c770c85233af592e54537f93f3831bde7e9a < c7241babf0855d8a6180cd1743ff0ec34de40b4e`\n- `Linux 5.18`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}