Bug 2492794 (CVE-2026-53164)

Summary:	CVE-2026-53164 kernel: iommu/dma: Do not try to iommu_map a 0 length region in swiotlb
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
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
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's input/output memory management unit (IOMMU) Direct Memory Access (DMA) subsystem, specifically within the software IOMMU bounce buffer (SWIOTLB) mechanism. This vulnerability occurs when the system attempts to map a zero-length memory region, which can be triggered by certain Thunderbolt NVMe drives passing unaligned memory buffers. This improper handling can lead to corruption of memory mappings, potentially causing system instability or a denial of service (DoS).	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-25 10:06:06 UTC

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

iommu/dma: Do not try to iommu_map a 0 length region in swiotlb

iommu_dma_iova_link_swiotlb() processes a mapping that is unaligned in three
parts, the head, middle and trailer. If the middle is empty because there
are no aligned pages it will call down to iommu_map() with a 0 size
which the iommupt implementation will fail as illegal.

It then tries to do an error unwind and starts from the wrong spot
corrupting the mapping so the eventual destruction triggers a WARN_ON.

Check for 0 length and avoid mapping and use offset not 0 as the starting
point to unlink.

This is frequently triggered by using some kinds of thunderbolt NVMe
drives that trigger forced SWIOTLB for unaligned memory. NVMe seems to
pass in oddly aligned buffers for the passthrough commands from smartctl
that hit this condition.

Comment 1 TEJ RATHI 2026-06-26 07:22:35 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062550-CVE-2026-53164-88ad@gregkh/T