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CVE-2026-90325

blk-cgroup: skip dying blkg in blkcg_activate_policy()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 6.1.17, 6.2.4, 6.6.157, 6.12.110, 6.18.52, and 1 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: skip dying blkg in blkcg_activate_policy() When switching IO schedulers on a block device, blkcg_activate_policy() can race with concurrent blkcg deletion, leading to a use-after-free in rcu_accelerate_cbs. T1: T2: blkg_destroy kill(&blkg->refcnt) // blkg->refcnt=1->0 blkg_release // call_rcu(__blkg_release) ... blkg_free_workfn ->pd_free_fn(pd) elv_iosched_store elevator_switch ... iterate blkg list blkg_get(blkg) // blkg->refcnt=0->1 list_del_init(&blkg->q_node) blkg_put(pinned_blkg) // blkg->refcnt=1->0 blkg_release // call_rcu again rcu_accelerate_cbs // uaf Fix this by checking hlist_unhashed(&blkg->blkcg_node) before getting a reference to the blkg. This is the same check used in blkg_destroy() to detect if a blkg has already been destroyed. If the blkg is already unhashed, skip processing it since it's being destroyed.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 81c1188905f88b77743d1fdeeedfc8cb7b67787d · fixed in b5dae1cd0d8368b4338430ff93403df67f0b8bcc; From bfe46d2efe46c5c952f982e2ca94fe2ec5e58e2a · fixed in 083b58373463a6e5ee60ecb135269348f68ad7df; From f1c006f1c6850c14040f8337753a63119bba39b9 · fixed in 1a267295b1ea6a6477963f3fda84adfecd48fcad; From f1c006f1c6850c14040f8337753a63119bba39b9 · fixed in 7337d012ca3fc3a6a2d1c8e2a19c6d97c38b410d; From f1c006f1c6850c14040f8337753a63119bba39b9 · fixed in 3d8c3da95c75a4d312e272fc7b4076dd3ba9115c; From f1c006f1c6850c14040f8337753a63119bba39b9 · fixed in d8c872901e6459339374e9eea80aa919176c2ccd; From f1c006f1c6850c14040f8337753a63119bba39b9 · fixed in 5e9220389920f33b6a804d50c548cd0cd1b04634; From 6.1.16 · fixed in 6.1.17; From 6.2.3 · fixed in 6.2.4

  • Linux Linux

    6.3

  • KernelLinux

    fixed in 6.1.17; From 6.2.0 · fixed in 6.2.4; From 6.3.0 · fixed in 6.6.157; fixed in 6.12.110; From 6.7.0 · fixed in 6.18.52; From 6.13.0 · fixed in 7.2.6

References 7

git.kernel.org