Bug 2480434 (CVE-2026-43494)

Summary:	CVE-2026-43494 kernel: net/rds: reset op_nents when zerocopy page pin fails
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
Version:	unspecified	CC:	kevinxue, 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, specifically within the `net/rds` module. When a zerocopy page pin operation fails, a counter used for memory management (`op_nents`) is not correctly reset. This can result in a double-free vulnerability, where the same memory is released twice. A local attacker could potentially exploit this to cause the system to crash (denial of service) or, in some cases, execute unauthorized code.	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 2026-05-21 12:01:28 UTC

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

net/rds: reset op_nents when zerocopy page pin fails

When iov_iter_get_pages2() fails in rds_message_zcopy_from_user(),
the pinned pages are released with put_page(), and
rm->data.op_mmp_znotifier is cleared.  But we fail to properly
clear rm->data.op_nents.

Later when rds_message_purge() is called from rds_sendmsg() the
cleanup loop iterates over the incorrectly non zero number of
op_nents and frees them again.

Fix this by properly resetting op_nents when it should be in
rds_message_zcopy_from_user().

Comment 1 Keith Grant 2026-05-21 14:49:40 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026052130-CVE-2026-43494-a65a@gregkh/T