CVE-2026-90326

Status: UPDATED  |  Advisory ID: CVE-2026-90326

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

blk-cgroup: fix race between policy activation and blkg destruction

When switching an IO scheduler on a block device, blkcg_activate_policy()

allocates blkg_policy_data (pd) for all blkgs attached to the queue.

However, blkcg_activate_policy() may race with concurrent blkcg deletion,

leading to use-after-free and memory leak issues.

The use-after-free occurs in the following race:

T1 (blkcg_activate_policy):

- Successfully allocates pd for blkg1 (loop0->queue, blkcgA)

- Fails to allocate pd for blkg2 (loop0->queue, blkcgB)

- Enters the enomem rollback path to release blkg1 resources

T2 (blkcg deletion):

- blkcgA is deleted concurrently

- blkg1 is freed via blkg_free_workfn()

- blkg1->pd is freed

T1 (continued):

- Rollback path accesses blkg1->pd->online after pd is freed

- Triggers use-after-free

In addition, blkg_free_workfn() frees pd before removing the blkg from

q->blkg_list. This allows blkcg_activate_policy() to allocate a new pd

for a blkg that is being destroyed, leaving the newly allocated pd

unreachable when the blkg is finally freed.

Fix these races by extending blkcg_mutex coverage to serialize

blkcg_activate_policy() rollback and blkg destruction, ensuring pd

lifecycle is synchronized with blkg list visibility. (NVD)

What to Do

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

References