{"id":"CVE-2026-90325","published":"2026-09-17T17:17:30.540","lastModified":"2026-09-18T18:17:53.960","description":"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.","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/083b58373463a6e5ee60ecb135269348f68ad7df","tags":[]},{"url":"https://git.kernel.org/stable/c/1a267295b1ea6a6477963f3fda84adfecd48fcad","tags":[]},{"url":"https://git.kernel.org/stable/c/3d8c3da95c75a4d312e272fc7b4076dd3ba9115c","tags":[]},{"url":"https://git.kernel.org/stable/c/5e9220389920f33b6a804d50c548cd0cd1b04634","tags":[]},{"url":"https://git.kernel.org/stable/c/7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d","tags":[]},{"url":"https://git.kernel.org/stable/c/b5dae1cd0d8368b4338430ff93403df67f0b8bcc","tags":[]},{"url":"https://git.kernel.org/stable/c/d8c872901e6459339374e9eea80aa919176c2ccd","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}