Bug 2464367 (CVE-2026-43045)

Summary:	CVE-2026-43045 kernel: mshv: Fix error handling in mshv_region_pin
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	unspecified	Docs Contact:
Priority:	unspecified
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 mshv module. Incorrect error handling in the mshv_region_pin function can lead to memory corruption. This occurs when the pin_user_pages_fast() operation returns a partial pin count, causing the system to use incompletely pinned memory regions. This issue can also result in a page reference leak during error cleanup.	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 2026-05-01 15:02:41 UTC

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

mshv: Fix error handling in mshv_region_pin

The current error handling has two issues:

First, pin_user_pages_fast() can return a short pin count (less than
requested but greater than zero) when it cannot pin all requested pages.
This is treated as success, leading to partially pinned regions being
used, which causes memory corruption.

Second, when an error occurs mid-loop, already pinned pages from the
current batch are not properly accounted for before calling
mshv_region_invalidate_pages(), causing a page reference leak.

Treat short pins as errors and fix partial batch accounting before
cleanup.

Comment 1 Keith Grant 2026-05-01 18:20:52 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050105-CVE-2026-43045-de58@gregkh/T