Bug 2546421 (CVE-2026-98268)

Summary:	CVE-2026-98268 kernel: perf: Fix null pointer access in is_include_guest_event()
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:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, 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 performance monitoring (perf) subsystem. This vulnerability allows a local user to cause a Denial of Service (DoS) by crashing the operating system. When a kernel module is unloaded while a performance event remains active, the kernel clears the associated monitoring pointer. Subsequently closing the event causes the kernel to access this null pointer, resulting in a kernel crash.	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 2026-10-06 09:18:23 UTC

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

perf: Fix null pointer access in is_include_guest_event()

A typical module unload occurring event when there is an active perf
connection leads to freeing of the pmu pointer. The call log is something
like:
 ..
 __pmu_detach_event
 pmu_detach_event
 pmu_detach_events
 perf_pmu_unregister
 ..

__pmu_detach_event() sets event->pmu to null. When the perf connection
finally is closed, the following stack trace is observed:

 Oops: general protection fault, kernel NULL pointer dereference
 ...
 RIP: 0010:_free_event+0x3e/0x370
 ...
 Call Trace:
 ...
 perf_event_release_kernel+0x260/0x2d0
 perf_release+0x12/0x20

A call to mediated_pmu_unaccount_event() inside _free_event() is the root
cause of this crash. Adding a check inside is_include_guest_event() ensures
we don't accidentally access a null pmu ptr. In addition to this, we will
now call mediated_pmu_unaccount_event() before clearing the pmu ptr so that
nr_include_guest_events counts are maintained correctly.

Comment 1 gkamathe 2026-10-10 20:12:05 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98268.mbox