Bug 2492755 (CVE-2026-53133)

Summary:	CVE-2026-53133 kernel: RDMA/umem: Fix truncation for block sizes >= 4G
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
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Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's RDMA/umem component. When the IOMMU (Input/Output Memory Management Unit) is used, a very large memory block can be split across multiple scatter-gather (SG) entries. During the reassembly of these split SG entries, an issue with truncation for block sizes greater than or equal to 4 gigabytes (4G) can lead to an overflow of 32-bit stack values. This results in the computation of incorrect DMA (Direct Memory Access) addresses, potentially causing data corruption or system instability.	Story Points:	---
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-25 10:04:02 UTC

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

RDMA/umem: Fix truncation for block sizes >= 4G

When the iommu is used the linearization of the mapping can give a single
block that is very large split across multiple SG entries.

When __rdma_block_iter_next() reassembles the split SG entries it is
overflowing the 32 bit stack values and computed the wrong DMA addresses
for blocks after the truncation.

Use the right types to hold DMA addresses.

Comment 1 Keith Grant 2026-06-25 23:14:29 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062542-CVE-2026-53133-de02@gregkh/T