# CVE-2025-40340: drm/xe: Fix oops in xe_gem_fault when running core_hotunplug test.

> A null pointer dereference in the Linux kernel's Xe GPU driver allows local attackers to cause a system crash via memory mapping operations.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Dec 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-40340, DEBIAN-CVE-2025-40340, GHSA-c24v-836h-jr7p, ROOT-OS-DEBIAN-12-CVE-2025-40340, ROOT-OS-DEBIAN-13-CVE-2025-40340, ROOT-OS-UBUNTU-2204-CVE-2025-40340, ROOT-OS-UBUNTU-2404-CVE-2025-40340, UBUNTU-CVE-2025-40340

## What is CVE-2025-40340?

CVE-2025-40340 is a vulnerability in Linux, published on 9 Dec 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:

drm/xe: Fix oops in xe_gem_fault when running core_hotunplug test.

I saw an oops in xe_gem_fault when running the xe-fast-feedback
testlist against the realtime kernel without debug options enabled.

The panic happens after core_hotunplug unbind-rebind finishes.
Presumably what happens is that a process mmaps, unlocks because
of the FAULT_FLAG_RETRY_NOWAIT logic, has no process memory left,
causing ttm_bo_vm_dummy_page() to return VM_FAULT_NOPAGE, since
there was nothing left to populate, and then oopses in
"mem_type_is_vram(tbo->resource->mem_type)" because tbo->resource
is NULL.

It's convoluted, but fits the data and explains the oops after
the test exits.

## Which versions are affected by CVE-2025-40340?


## How do I fix CVE-2025-40340?

Apply the vendor's patch.

## Is CVE-2025-40340 being exploited?

There is no known exploitation of CVE-2025-40340 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-40340 and fix it if it is affected.

What it is: CVE-2025-40340 is a vulnerability in Linux, published on 9 Dec 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-2025-40340 in the wild and no public exploit code.

Affected product: Linux. 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-2025-40340/ (Markdown: https://insights.sbomify.com/CVE-2025-40340/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-40340
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-40340
- OSV: https://osv.dev/vulnerability/CVE-2025-40340

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-40340/
Summaries are generated and may contain mistakes; the official description above is the record.