Bug 2546467 (CVE-2026-98176)

Summary: CVE-2026-98176 kernel: drm/amdkfd: Avoid integer underflow with ffs in EOP ring size calc
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's AMD GPU driver (amdkfd). An integer underflow vulnerability during the calculation of the End of Pipe (EOP) ring buffer size can lead to improper hardware queue configuration. A local user could potentially exploit this issue to cause system instability, resulting in a Denial of Service (DoS).
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Description OSIDB Bzimport 2026-10-06 09:25:31 UTC 
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)
Comment 1 Mauro Matteo Cascella 2026-10-08 11:08:57 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98176.mbox