# CVE-2022-49412: bfq: Avoid merging queues with different parents

> A use-after-free vulnerability in the Linux kernel BFQ I/O scheduler allows local attackers to potentially execute code or escalate privileges.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 Feb 2025
- **Updated:** 5 Aug 2026
- **Also known as:** DEBIAN-CVE-2022-49412, GHSA-r26p-qcvf-g5c5, UBUNTU-CVE-2022-49412

## What is CVE-2022-49412?

CVE-2022-49412 is a high-severity use after free vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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

bfq: Avoid merging queues with different parents

It can happen that the parent of a bfqq changes between the moment we
decide two queues are worth to merge (and set bic->stable_merge_bfqq)
and the moment bfq_setup_merge() is called. This can happen e.g. because
the process submitted IO for a different cgroup and thus bfqq got
reparented. It can even happen that the bfqq we are merging with has
parent cgroup that is already offline and going to be destroyed in which
case the merge can lead to use-after-free issues such as:

BUG: KASAN: use-after-free in __bfq_deactivate_entity+0x9cb/0xa50
Read of size 8 at addr ffff88800693c0c0 by task runc:[2:INIT]/10544

CPU: 0 PID: 10544 Comm: runc:[2:INIT] Tainted: G            E     5.15.2-0.g5fb85fd-default #1 openSUSE Tumbleweed (unreleased) f1f3b891c72369aebecd2e43e4641a6358867c70
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014
Call Trace:
 <IRQ>
 dump_stack_lvl+0x46/0x5a
 print_address_description.constprop.0+0x1f/0x140
 ? __bfq_deactivate_entity+0x9cb/0xa50
 kasan_report.cold+0x7f/0x11b
 ? __bfq_deactivate_entity+0x9cb/0xa50
 __bfq_deactivate_entity+0x9cb/0xa50
 ? update_curr+0x32f/0x5d0
 bfq_deactivate_entity+0xa0/0x1d0
 bfq_del_bfqq_busy+0x28a/0x420
 ? resched_curr+0x116/0x1d0
 ? bfq_requeue_bfqq+0x70/0x70
 ? check_preempt_wakeup+0x52b/0xbc0
 __bfq_bfqq_expire+0x1a2/0x270
 bfq_bfqq_expire+0xd16/0x2160
 ? try_to_wake_up+0x4ee/0x1260
 ? bfq_end_wr_async_queues+0xe0/0xe0
 ? _raw_write_unlock_bh+0x60/0x60
 ? _raw_spin_lock_irq+0x81/0xe0
 bfq_idle_slice_timer+0x109/0x280
 ? bfq_dispatch_request+0x4870/0x4870
 __hrtimer_run_queues+0x37d/0x700
 ? enqueue_hrtimer+0x1b0/0x1b0
 ? kvm_clock_get_cycles+0xd/0x10
 ? ktime_get_update_offsets_now+0x6f/0x280
 hrtimer_interrupt+0x2c8/0x740

Fix the problem by checking that the parent of the two bfqqs we are
merging in bfq_setup_merge() is the same.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2022-49412?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49412?

Apply the vendor's patch.

## Is CVE-2022-49412 being exploited?

There is no known exploitation of CVE-2022-49412 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2022-49412 and fix it if it is affected.

What it is: CVE-2022-49412 is a high-severity use after free vulnerability in Linux kernel, published on 26 Feb 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2022-49412 in the wild and no public exploit code.

Affected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2022-49412/ (Markdown: https://insights.sbomify.com/CVE-2022-49412/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49412
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49412
- OSV: https://osv.dev/vulnerability/CVE-2022-49412

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49412/
Summaries are generated and may contain mistakes; the official description above is the record.