Bug 2527875 (CVE-2026-80736)

Summary:	CVE-2026-80736 kernel: thunderbolt: Fix bandwidth group reservation indexing
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	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 Thunderbolt driver. The `tb_consumed_dp_bandwidth()` function attempts to access an array beyond its allocated memory, specifically when handling bandwidth group IDs. This out-of-bounds read can lead to an incorrect calculation of reserved bandwidth for Thunderbolt devices, potentially affecting system stability or resource allocation.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-03 08:43:33 UTC

In the Linux kernel, the following vulnerability has been resolved:

thunderbolt: Fix bandwidth group reservation indexing

Valid bandwidth group IDs range from 1 through MAX_GROUPS, while Group
ID 0 is reserved. tb_consumed_dp_bandwidth() uses the Group ID directly
to index its local group_reserved[] array.

The array currently has MAX_GROUPS entries, so its valid indices are 0
through MAX_GROUPS - 1. Group ID MAX_GROUPS therefore accesses one
element past the end, and the final group's reserved bandwidth is not
included when the array is summed.

Give group_reserved[] MAX_GROUPS + 1 entries so direct Group ID
indexing covers the reserved ID 0 and valid IDs 1 through MAX_GROUPS.

Comment 1 Mauro Matteo Cascella 2026-09-04 09:20:50 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80736.mbox