# CVE-2024-43863: drm/vmwgfx: Fix a deadlock in dma buf fence polling

> A deadlock in the vmwgfx driver's fence polling can cause system stalls or denial of service, particularly affecting KDE users.

- **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:** 20 Aug 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-48507, BELL-CVE-2024-43863, DEBIAN-CVE-2024-43863, GHSA-f95q-fwq6-mx8w, ROOT-OS-DEBIAN-11-CVE-2024-43863, UBUNTU-CVE-2024-43863

## What is CVE-2024-43863?

CVE-2024-43863 is a medium-severity vulnerability in Linux kernel, published on 20 Aug 2024. 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:

drm/vmwgfx: Fix a deadlock in dma buf fence polling

Introduce a version of the fence ops that on release doesn't remove
the fence from the pending list, and thus doesn't require a lock to
fix poll->fence wait->fence unref deadlocks.

vmwgfx overwrites the wait callback to iterate over the list of all
fences and update their status, to do that it holds a lock to prevent
the list modifcations from other threads. The fence destroy callback
both deletes the fence and removes it from the list of pending
fences, for which it holds a lock.

dma buf polling cb unrefs a fence after it's been signaled: so the poll
calls the wait, which signals the fences, which are being destroyed.
The destruction tries to acquire the lock on the pending fences list
which it can never get because it's held by the wait from which it
was called.

Old bug, but not a lot of userspace apps were using dma-buf polling
interfaces. Fix those, in particular this fixes KDE stalls/deadlock.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2024-43863?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-43863?

Apply the vendor's patch.

## Is CVE-2024-43863 being exploited?

There is no known exploitation of CVE-2024-43863 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-2024-43863 and fix it if it is affected.

What it is: CVE-2024-43863 is a medium-severity vulnerability in Linux kernel, published on 20 Aug 2024. 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-2024-43863 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-2024-43863/ (Markdown: https://insights.sbomify.com/CVE-2024-43863/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-43863
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-43863
- OSV: https://osv.dev/vulnerability/CVE-2024-43863

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-43863/
Summaries are generated and may contain mistakes; the official description above is the record.