# CVE-2026-97900: drm/drm_exec: fix up contended obj when num_objects is 0

> A local attacker can cause an infinite loop and system hang in the Linux kernel DRM subsystem by triggering contention with empty object arrays.

- **Severity:** Not scored
- **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:** 25 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-104286, BELL-CVE-2026-97900, DEBIAN-CVE-2026-97900, GHSA-fx27-pfff-j2g5, UBUNTU-CVE-2026-97900

## What is CVE-2026-97900?

CVE-2026-97900 is a denial of service vulnerability in Linux, published on 25 Sep 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:

drm/drm_exec: fix up contended obj when num_objects is 0

drm_exec_prepare_array() silently returns success without calling
drm_exec_lock_contended() when num_objects is zero. This breaks the
invariant upheld by drm_exec_lock_obj(), where every entry point into
the locking sequence must first attempt to lock any previously
contended object before proceeding.

Drivers that chain multiple drm_exec_prepare_array() calls per
drm_exec_until_all_locked() iteration (e.g. amdgpu's userq signal/wait
ioctls, which prepare separate read and write BO arrays) can pass an
empty array for one of the two calls. If contention is hit while
preparing the non-empty array, exec->contended is set and the loop
retries; on retry, the empty-array call preceding it is a no-op that
never clears exec->contended, so drm_exec_retry_on_contention()
immediately jumps back to the top of the loop without ever reaching
the call that would resolve the contention. This spins forever.

Fix it by having drm_exec_prepare_array() call drm_exec_lock_contended()
directly when num_objects is zero, so a pending contended object dont
loop infinitely.

## Which versions are affected by CVE-2026-97900?


## How do I fix CVE-2026-97900?

Apply the vendor's patch.

## Is CVE-2026-97900 being exploited?

There is no known exploitation of CVE-2026-97900 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97900 and fix it if it is affected.

What it is: CVE-2026-97900 is a denial of service vulnerability in Linux, published on 25 Sep 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-2026-97900 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-2026-97900/ (Markdown: https://insights.sbomify.com/CVE-2026-97900/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97900
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97900
- OSV: https://osv.dev/vulnerability/CVE-2026-97900

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-97900/
Summaries are generated and may contain mistakes; the official description above is the record.