CVE-2026-90325

Status: UPDATED  |  Advisory ID: CVE-2026-90325

Key Details

Affected Products, Subsystems & Sectors

What to Know

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References