Bug 2507074 (CVE-2026-64258)

Summary:	CVE-2026-64258 kernel: fuse-uring: remove request-less entries from ent_w_req_queue to fix NULL deref
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
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 `fuse-uring` component of the Linux kernel. When a copy operation to the userspace ring buffer fails, a request can be terminated improperly, leading to a NULL pointer dereference. This vulnerability could allow a local attacker to cause a system crash, resulting in 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 2026-07-25 10:03:38 UTC

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

fuse-uring: remove request-less entries from ent_w_req_queue to fix NULL deref

If a copy into the userspace ring buffer fails, a request will be
terminated and fuse_uring_req_end() will set ent->fuse_req to NULL but
it will leave the entry on ent_w_req_queue in FRRS_FUSE_REQ state. This
can lead to a NULL deref if the request expiration logic scans
ent_w_req_queue in the window before the entry is moved off it.

Fix this by taking the entry off ent_w_req_queue and changing its state
from FRRS_FUSE_REQ to FRRS_INVALID before terminating the request.

Comment 1 TEJ RATHI 2026-07-30 05:28:37 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072556-CVE-2026-64258-6e18@gregkh/T