# CVE-2026-53331: slimbus: qcom-ngd-ctrl: Avoid ABBA on tx_lock/ctrl->lock

> A race condition in the Qualcomm NGD controller driver can cause a deadlock, leading to a 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 Jul 2026
- **Updated:** 1 Jul 2026
- **Also known as:** BELL-CVE-2026-53331, DEBIAN-CVE-2026-53331, GHSA-2xvr-5mwv-w22p, ROOT-OS-DEBIAN-12-CVE-2026-53331, ROOT-OS-UBUNTU-2204-CVE-2026-53331, ROOT-OS-UBUNTU-2404-CVE-2026-53331, UBUNTU-CVE-2026-53331

## What is CVE-2026-53331?

CVE-2026-53331 is a medium-severity vulnerability in Linux kernel, published on 1 Jul 2026. 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:

slimbus: qcom-ngd-ctrl: Avoid ABBA on tx_lock/ctrl->lock

During the SSR/PDR down notification the tx_lock is taken with the
intent to provide synchronization with active DMA transfers.

But during this period qcom_slim_ngd_down() is invoked, which ends up in
slim_report_absent(), which takes the slim_controller lock. In multiple
other codepaths these two locks are taken in the opposite order (i.e.
slim_controller then tx_lock).

The result is a lockdep splat, and a possible deadlock:

  rprocctl/449 is trying to acquire lock:
  ffff00009793e620 (&ctrl->lock){+.+.}-{4:4}, at: slim_report_absent (drivers/slimbus/core.c:322) slimbus

  but task is already holding lock:
  ffff00009793fb50 (&ctrl->tx_lock){+.+.}-{4:4}, at: qcom_slim_ngd_ssr_pdr_notify (drivers/slimbus/qcom-ngd-ctrl.c:1475) slim_qcom_ngd_ctrl

  which lock already depends on the new lock.

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&ctrl->tx_lock);
                                lock(&ctrl->lock);
                                lock(&ctrl->tx_lock);
   lock(&ctrl->lock);

The assumption is that the comment refers to the desire to not call
qcom_slim_ngd_exit_dma() while we have an ongoing DMA TX transaction.
But any such transaction is initiated and completed within a single
qcom_slim_ngd_xfer_msg().

Prior to calling qcom_slim_ngd_exit_dma() the slim_controller is torn
down, all child devices are notified that the slimbus is gone and the
child devices are removed.

Stop taking the tx_lock in qcom_slim_ngd_ssr_pdr_notify() to avoid the
deadlock.

## Which versions are affected by CVE-2026-53331?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2026-53331?

Apply the vendor's patch.

## Is CVE-2026-53331 being exploited?

There is no known exploitation of CVE-2026-53331 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-2026-53331 and fix it if it is affected.

What it is: CVE-2026-53331 is a medium-severity vulnerability in Linux kernel, published on 1 Jul 2026. 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-2026-53331 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-2026-53331/ (Markdown: https://insights.sbomify.com/CVE-2026-53331/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-53331
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-53331
- OSV: https://osv.dev/vulnerability/CVE-2026-53331

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-53331/
Summaries are generated and may contain mistakes; the official description above is the record.