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

CVE-2026-98176 is fixed in linux on 1 platform by DEBIAN-CVE-2026-98176 (version 7.2.8-1), released October 6, 2026. It is not reported as exploited. Patch Radar priority: Urgent.

- Web page: https://patchblox.com/security/cve/CVE-2026-98176
- Priority: Urgent
- CVSS: 9.8 (Critical)
- EPSS: 0.0017
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Oct 6, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-98176

## 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)

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 14 | 7.2.8-1 | [DEBIAN-CVE-2026-98176](https://patchblox.com/security/data/fix/linux/debian-cve-2026-98176.md) | Oct 6, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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