Bug 2516336 (CVE-2026-72006)

Summary:	CVE-2026-72006 kernel: net/mlx5: free mlx5_st_idx_data on final dealloc
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:	rhel-process-autobot, 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 mlx5 driver. Repeated allocation and release of mkeys with TPH steering-tag hints can cause a memory leak of `struct mlx5_st_idx_data`. This unreferenced memory accumulates over time, potentially leading to resource exhaustion and a Denial of Service (DoS) for affected systems.	Story Points:	---
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Last Closed:		Type:	---
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-08-15 06:07:11 UTC

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

net/mlx5: free mlx5_st_idx_data on final dealloc

Workloads that repeatedly allocate and release mkeys carrying TPH
steering-tag hints (e.g. churning RDMA MRs) leak one
struct mlx5_st_idx_data per cycle; kmemleak flags it as unreferenced
and the kmalloc slab grows over time.

When the last reference to an ST table entry is dropped,
mlx5_st_dealloc_index() removed the entry from idx_xa but the backing
mlx5_st_idx_data allocation was never freed.

Free idx_data after the xa_erase() so the lifetime of the bookkeeping
struct matches the lifetime of the ST entry it tracks.

Comment 1 Keith Grant 2026-08-17 15:13:32 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081507-CVE-2026-72006-c8b1@gregkh/T