# CVE-2022-49901: blk-mq: Fix kmemleak in blk_mq_init_allocated_queue

> A memory leak in the Linux kernel block layer can lead to resource exhaustion and denial of service when loading specific modules.

- **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:** AZL-61715, DEBIAN-CVE-2022-49901, GHSA-pmj7-4375-32j4, ROOT-OS-DEBIAN-11-CVE-2022-49901, ROOT-OS-UBUNTU-2204-CVE-2022-49901, UBUNTU-CVE-2022-49901

## What is CVE-2022-49901?

CVE-2022-49901 is a medium-severity memory corruption 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:

blk-mq: Fix kmemleak in blk_mq_init_allocated_queue

There is a kmemleak caused by modprobe null_blk.ko

unreferenced object 0xffff8881acb1f000 (size 1024):
  comm "modprobe", pid 836, jiffies 4294971190 (age 27.068s)
  hex dump (first 32 bytes):
    00 00 00 00 ad 4e ad de ff ff ff ff 00 00 00 00  .....N..........
    ff ff ff ff ff ff ff ff 00 53 99 9e ff ff ff ff  .........S......
  backtrace:
    [<000000004a10c249>] kmalloc_node_trace+0x22/0x60
    [<00000000648f7950>] blk_mq_alloc_and_init_hctx+0x289/0x350
    [<00000000af06de0e>] blk_mq_realloc_hw_ctxs+0x2fe/0x3d0
    [<00000000e00c1872>] blk_mq_init_allocated_queue+0x48c/0x1440
    [<00000000d16b4e68>] __blk_mq_alloc_disk+0xc8/0x1c0
    [<00000000d10c98c3>] 0xffffffffc450d69d
    [<00000000b9299f48>] 0xffffffffc4538392
    [<0000000061c39ed6>] do_one_initcall+0xd0/0x4f0
    [<00000000b389383b>] do_init_module+0x1a4/0x680
    [<0000000087cf3542>] load_module+0x6249/0x7110
    [<00000000beba61b8>] __do_sys_finit_module+0x140/0x200
    [<00000000fdcfff51>] do_syscall_64+0x35/0x80
    [<000000003c0f1f71>] entry_SYSCALL_64_after_hwframe+0x46/0xb0

That is because q->ma_ops is set to NULL before blk_release_queue is
called.

blk_mq_init_queue_data
  blk_mq_init_allocated_queue
    blk_mq_realloc_hw_ctxs
      for (i = 0; i < set->nr_hw_queues; i++) {
        old_hctx = xa_load(&q->hctx_table, i);
        if (!blk_mq_alloc_and_init_hctx(.., i, ..))		[1]
          if (!old_hctx)
	    break;

      xa_for_each_start(&q->hctx_table, j, hctx, j)
        blk_mq_exit_hctx(q, set, hctx, j); 			[2]

    if (!q->nr_hw_queues)					[3]
      goto err_hctxs;

  err_exit:
      q->mq_ops = NULL;			  			[4]

  blk_put_queue
    blk_release_queue
      if (queue_is_mq(q))					[5]
        blk_mq_release(q);

[1]: blk_mq_alloc_and_init_hctx failed at i != 0.
[2]: The hctxs allocated by [1] are moved to q->unused_hctx_list and
will be cleaned up in blk_mq_release.
[3]: q->nr_hw_queues is 0.
[4]: Set q->mq_ops to NULL.
[5]: queue_is_mq returns false due to [4]. And blk_mq_release
will not be called. The hctxs in q->unused_hctx_list are leaked.

To fix it, call blk_release_queue in exception path.

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

## Which versions are affected by CVE-2022-49901?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-49901?

Apply the vendor's patch.

## Is CVE-2022-49901 being exploited?

There is no known exploitation of CVE-2022-49901 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-2022-49901 and fix it if it is affected.

What it is: CVE-2022-49901 is a medium-severity memory corruption 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-2022-49901 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-2022-49901/ (Markdown: https://insights.sbomify.com/CVE-2022-49901/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-49901
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-49901
- OSV: https://osv.dev/vulnerability/CVE-2022-49901

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-49901/
Summaries are generated and may contain mistakes; the official description above is the record.