{"id":"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-\u003erefcnt) // blkg-\u003erefcnt=1-\u003e0\n                                  blkg_release // call_rcu(__blkg_release)\n                                  ...\n                                  blkg_free_workfn\n                                  -\u003epd_free_fn(pd)\nelv_iosched_store\nelevator_switch\n...\niterate blkg list\nblkg_get(blkg) // blkg-\u003erefcnt=0-\u003e1\n                                  list_del_init(&blkg-\u003eq_node)\nblkg_put(pinned_blkg) // blkg-\u003erefcnt=1-\u003e0\nblkg_release // call_rcu again\nrcu_accelerate_cbs // uaf\n\nFix this by checking hlist_unhashed(&blkg-\u003eblkcg_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.","modified":"2026-09-18T03:48:37.252060160Z","published":"2026-09-17T16:08:40.710Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90325.json","cna_assigner":"Linux"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"81c1188905f88b77743d1fdeeedfc8cb7b67787d"},{"fixed":"b5dae1cd0d8368b4338430ff93403df67f0b8bcc"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a"},{"fixed":"083b58373463a6e5ee60ecb135269348f68ad7df"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f1c006f1c6850c14040f8337753a63119bba39b9"},{"fixed":"1a267295b1ea6a6477963f3fda84adfecd48fcad"},{"fixed":"7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d"},{"fixed":"3d8c3da95c75a4d312e272fc7b4076dd3ba9115c"},{"fixed":"d8c872901e6459339374e9eea80aa919176c2ccd"},{"fixed":"5e9220389920f33b6a804d50c548cd0cd1b04634"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.1.16"},{"fixed":"6.1.17"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"6.2.3"},{"fixed":"6.2.4"}]}],"versions":["v6.1.16","v6.2.3"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90325.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.1.17"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.2.4"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.3.0"},{"fixed":"6.6.157"},{"fixed":"6.12.110"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.18.52"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"7.2.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-90325.json"}}],"schema_version":"1.9.0"}