# CVE-2022-50534: dm thin: Use last transaction's pmd->root when commit failed

> A flaw in the Linux kernel's dm thin driver causes a softlockup and kernel panic when metadata commit fails, leading to 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:** 7 Oct 2025
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2022-50534, GHSA-84fr-rw9r-j8p4, UBUNTU-CVE-2022-50534

## What is CVE-2022-50534?

CVE-2022-50534 is a medium-severity denial of service vulnerability in Linux kernel, published on 7 Oct 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:

dm thin: Use last transaction's pmd->root when commit failed

Recently we found a softlock up problem in dm thin pool btree lookup
code due to corrupted metadata:

 Kernel panic - not syncing: softlockup: hung tasks
 CPU: 7 PID: 2669225 Comm: kworker/u16:3
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996)
 Workqueue: dm-thin do_worker [dm_thin_pool]
 Call Trace:
   <IRQ>
   dump_stack+0x9c/0xd3
   panic+0x35d/0x6b9
   watchdog_timer_fn.cold+0x16/0x25
   __run_hrtimer+0xa2/0x2d0
   </IRQ>
   RIP: 0010:__relink_lru+0x102/0x220 [dm_bufio]
   __bufio_new+0x11f/0x4f0 [dm_bufio]
   new_read+0xa3/0x1e0 [dm_bufio]
   dm_bm_read_lock+0x33/0xd0 [dm_persistent_data]
   ro_step+0x63/0x100 [dm_persistent_data]
   btree_lookup_raw.constprop.0+0x44/0x220 [dm_persistent_data]
   dm_btree_lookup+0x16f/0x210 [dm_persistent_data]
   dm_thin_find_block+0x12c/0x210 [dm_thin_pool]
   __process_bio_read_only+0xc5/0x400 [dm_thin_pool]
   process_thin_deferred_bios+0x1a4/0x4a0 [dm_thin_pool]
   process_one_work+0x3c5/0x730

Following process may generate a broken btree mixed with fresh and
stale btree nodes, which could get dm thin trapped in an infinite loop
while looking up data block:
 Transaction 1: pmd->root = A, A->B->C   // One path in btree
                pmd->root = X, X->Y->Z   // Copy-up
 Transaction 2: X,Z is updated on disk, Y write failed.
                // Commit failed, dm thin becomes read-only.
                process_bio_read_only
		 dm_thin_find_block
		  __find_block
		   dm_btree_lookup(pmd->root)
The pmd->root points to a broken btree, Y may contain stale node
pointing to any block, for example X, which gets dm thin trapped into
a dead loop while looking up Z.

Fix this by setting pmd->root in __open_metadata(), so that dm thin
will use the last transaction's pmd->root if commit failed.

Fetch a reproducer in [Link].

Linke: https://bugzilla.kernel.org/show_bug.cgi?id=216790

## Which versions are affected by CVE-2022-50534?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2022-50534?

Apply the vendor's patch.

## Is CVE-2022-50534 being exploited?

There is no known exploitation of CVE-2022-50534 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-2022-50534 and fix it if it is affected.

What it is: CVE-2022-50534 is a medium-severity denial of service vulnerability in Linux kernel, published on 7 Oct 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-2022-50534 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-2022-50534/ (Markdown: https://insights.sbomify.com/CVE-2022-50534/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-50534
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-50534
- OSV: https://osv.dev/vulnerability/CVE-2022-50534

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-50534/
Summaries are generated and may contain mistakes; the official description above is the record.