# CVE-2026-98176: drm/amdkfd: Avoid integer underflow with ffs in EOP ring size calc

> A local attacker can trigger an integer underflow in the AMD KFD driver, potentially causing a denial of service.

- **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:** 6 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-106263, BELL-CVE-2026-98176, DEBIAN-CVE-2026-98176, GHSA-mv47-6r4w-p28q, UBUNTU-CVE-2026-98176

## What is CVE-2026-98176?

CVE-2026-98176 is a vulnerability in Linux, published on 6 Oct 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/amdkfd: Avoid integer underflow with ffs in EOP ring size calc

The low 6 bits of cp_hqd_eop_control store the base-2 logarithm
of the EOP ring size. This was calculated as

ffs(q->eop_ring_buffer_size / sizeof(unsigned int)) - 1 - 1

But ffs can in theory return 1 or 0, so this could underflow
(although in practice the ring buffer size cannot be less than 4096).

Change this to

ffs(q->eop_ring_buffer_size / sizeof(unsigned int) / 4)

using properties of logarithms.

(cherry picked from commit 4f18c56630383c14bfc6b2d65f88f2f895d2121a)

## Which versions are affected by CVE-2026-98176?


## How do I fix CVE-2026-98176?

Apply the vendor's patch.

## Is CVE-2026-98176 being exploited?

There is no known exploitation of CVE-2026-98176 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98176 and fix it if it is affected.

What it is: CVE-2026-98176 is a vulnerability in Linux, published on 6 Oct 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-2026-98176 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-2026-98176/ (Markdown: https://insights.sbomify.com/CVE-2026-98176/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98176
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98176
- OSV: https://osv.dev/vulnerability/CVE-2026-98176

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98176/
Summaries are generated and may contain mistakes; the official description above is the record.