Bug 2536273 (CVE-2026-93196)

Summary:	CVE-2026-93196 kernel: nvdimm: virtio_pmem: refcount requests for token lifetime
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
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 virtio_pmem module. This use-after-free vulnerability occurs due to incorrect management of memory requests. When a request is prematurely freed while still being referenced, a subsequent attempt to access it can lead to memory corruption. This could allow a local attacker to cause system instability or 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 2026-09-17 17:14:17 UTC

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

nvdimm: virtio_pmem: refcount requests for token lifetime

KASAN reports slab-use-after-free in __wake_up_common():
BUG: KASAN: slab-use-after-free in __wake_up_common+0x114/0x160
Read of size 8 at addr ffff88810fdcb710 by task swapper/0/0

CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted
6.19.0-next-20260220-00006-g1eae5f204ec3 #4 PREEMPT(full)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Arch Linux
1.17.0-2-2 04/01/2014
Call Trace:
 <IRQ>
 dump_stack_lvl+0x6d/0xb0
 print_report+0x170/0x4e2
 ? __pfx__raw_spin_lock_irqsave+0x10/0x10
 ? __virt_addr_valid+0x1dc/0x380
 kasan_report+0xbc/0xf0
 ? __wake_up_common+0x114/0x160
 ? __wake_up_common+0x114/0x160
 __wake_up_common+0x114/0x160
 ? __pfx__raw_spin_lock_irqsave+0x10/0x10
 __wake_up+0x36/0x60
 virtio_pmem_host_ack+0x11d/0x3b0
 ? sched_balance_domains+0x29f/0xb00
 ? __pfx_virtio_pmem_host_ack+0x10/0x10
 ? _raw_spin_lock_irqsave+0x98/0x100
 ? __pfx__raw_spin_lock_irqsave+0x10/0x10
 vring_interrupt+0x1c9/0x5e0
 ? __pfx_vp_interrupt+0x10/0x10
 vp_vring_interrupt+0x87/0x100
 ? __pfx_vp_interrupt+0x10/0x10
 __handle_irq_event_percpu+0x17f/0x550
 ? __pfx__raw_spin_lock+0x10/0x10
 handle_irq_event+0xab/0x1c0
 handle_fasteoi_irq+0x276/0xae0
 __common_interrupt+0x65/0x130
 common_interrupt+0x78/0xa0
 </IRQ>

virtio_pmem_host_ack() wakes a request that has already been freed by the
submitter.

This happens when the request token is still reachable via the virtqueue,
but virtio_pmem_flush() returns and frees it.

Fix the token lifetime by refcounting struct virtio_pmem_request.
virtio_pmem_flush() holds a submitter reference, and the virtqueue holds an
extra reference once the request is queued. The completion path drops the
virtqueue reference, and the submitter drops its reference before
returning.

Comment 1 gkamathe 2026-09-18 09:17:23 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93196.mbox