# CVE-2022-49902: block: Fix possible memory leak for rq_wb on add_disk failure

> A memory leak in the Linux kernel block layer during disk addition failure can lead to resource exhaustion and denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 1 May 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-49902, GHSA-8p4q-63f6-rqfp, UBUNTU-CVE-2022-49902

## What is CVE-2022-49902?

CVE-2022-49902 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 May 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:

block: Fix possible memory leak for rq_wb on add_disk failure

kmemleak reported memory leaks in device_add_disk():

kmemleak: 3 new suspected memory leaks

unreferenced object 0xffff88800f420800 (size 512):
  comm "modprobe", pid 4275, jiffies 4295639067 (age 223.512s)
  hex dump (first 32 bytes):
    04 00 00 00 08 00 00 00 01 00 00 00 00 00 00 00  ................
    00 e1 f5 05 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<00000000d3662699>] kmalloc_trace+0x26/0x60
    [<00000000edc7aadc>] wbt_init+0x50/0x6f0
    [<0000000069601d16>] wbt_enable_default+0x157/0x1c0
    [<0000000028fc393f>] blk_register_queue+0x2a4/0x420
    [<000000007345a042>] device_add_disk+0x6fd/0xe40
    [<0000000060e6aab0>] nbd_dev_add+0x828/0xbf0 [nbd]
    ...

It is because the memory allocated in wbt_enable_default() is not
released in device_add_disk() error path.
Normally, these memory are freed in:

del_gendisk()
  rq_qos_exit()
    rqos->ops->exit(rqos);
      wbt_exit()

So rq_qos_exit() is called to free the rq_wb memory for wbt_init().
However in the error path of device_add_disk(), only
blk_unregister_queue() is called and make rq_wb memory leaked.

Add rq_qos_exit() to the error path to fix it.

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2022-49902?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49902?

Apply the vendor's patch.

## Is CVE-2022-49902 being exploited?

There is no known exploitation of CVE-2022-49902 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-2022-49902 and fix it if it is affected.

What it is: CVE-2022-49902 is a medium-severity denial of service vulnerability in Linux kernel, published on 1 May 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-2022-49902 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-2022-49902/ (Markdown: https://insights.sbomify.com/CVE-2022-49902/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49902
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49902
- OSV: https://osv.dev/vulnerability/CVE-2022-49902

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49902/
Summaries are generated and may contain mistakes; the official description above is the record.