{"id":"CVE-2026-90325","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-90325","summary":"blk-cgroup: skip dying blkg in blkcg_activate_policy()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nblk-cgroup: skip dying blkg in blkcg_activate_policy()\n\nWhen switching IO schedulers on a block device, blkcg_activate_policy()\ncan race with concurrent blkcg deletion, leading to a use-after-free in\nrcu_accelerate_cbs.\n\nT1:                               T2:\n                                  blkg_destroy\n                                  kill(&blkg->refcnt) // blkg->refcnt=1->0\n                                  blkg_release // call_rcu(__blkg_release)\n                                  ...\n                                  blkg_free_workfn\n                                  ->pd_free_fn(pd)\nelv_iosched_store\nelevator_switch\n...\niterate blkg list\nblkg_get(blkg) // blkg->refcnt=0->1\n                                  list_del_init(&blkg->q_node)\nblkg_put(pinned_blkg) // blkg->refcnt=1->0\nblkg_release // call_rcu again\nrcu_accelerate_cbs // uaf\n\nFix this by checking hlist_unhashed(&blkg->blkcg_node) before getting\na reference to the blkg. This is the same check used in blkg_destroy()\nto detect if a blkg has already been destroyed. If the blkg is already\nunhashed, skip processing it since it's being destroyed.","published":"2026-09-17T16:08:40.710Z","modified":"2026-09-19T03:47:25.888707370Z","cvss":{"score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"6.1.17"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df"},{"type":"WEB","url":"https://git.kernel.org/stable/c/1a267295b1ea6a6477963f3fda84adfecd48fcad"},{"type":"WEB","url":"https://git.kernel.org/stable/c/3d8c3da95c75a4d312e272fc7b4076dd3ba9115c"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e9220389920f33b6a804d50c548cd0cd1b04634"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d8c872901e6459339374e9eea80aa919176c2ccd"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90325.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-90325"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-19T03:47:25.888707370Z"}}