Bug 2546416 (CVE-2026-98177)

Summary: CVE-2026-98177 kernel: drm/amdkfd: Avoid integer underflow in EOP ring size calculation
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). A local user could trigger a Denial of Service (DoS) or system instability due to an integer underflow vulnerability during the calculation of the End of Pipe (EOP) ring buffer size. Under specific conditions, this improper calculation could lead to misconfigured hardware queue controls and unexpected driver behavior.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-10-06 09:17:06 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amdkfd: Avoid integer underflow in EOP ring size calculation.

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

order_base_2(q->eop_ring_buffer_size / 4) - 1

But order_base_2 can in theory return 0, so this could underflow
(although in practice the ring buffer size cannot be less than 4096).

Change this to

order_base_2(q->eop_ring_buffer_size / 8)

using properties of logarithms.

Also add to the above comment to make the mathematics more clear.

(cherry picked from commit f0f43fcf8b2b3a924cad9444340921c96ed5f634)