linkwatch: use __dev_put() in callers to prevent UAF

MITRE NVD CVE.ORG Print: PDF PDF

Summary

CVECVE-2026-23192
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-02-14 17:15:57 UTC
Updated2026-04-03 14:16:26 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: linkwatch: use __dev_put() in callers to prevent UAF After linkwatch_do_dev() calls __dev_put() to release the linkwatch reference, the device refcount may drop to 1. At this point, netdev_run_todo() can proceed (since linkwatch_sync_dev() sees an empty list and returns without blocking), wait for the refcount to become 1 via netdev_wait_allrefs_any(), and then free the device via kobject_put(). This creates a use-after-free when __linkwatch_run_queue() tries to call netdev_unlock_ops() on the already-freed device. Note that adding netdev_lock_ops()/netdev_unlock_ops() pair in netdev_run_todo() before kobject_put() would not work, because netdev_lock_ops() is conditional - it only locks when netdev_need_ops_lock() returns true. If the device doesn't require ops_lock, linkwatch won't hold any lock, and netdev_run_todo() acquiring the lock won't provide synchronization. Fix this by moving __dev_put() from linkwatch_do_dev() to its callers. The device reference logically pairs with de-listing the device, so it's reasonable for the caller that did the de-listing to release it. This allows placing __dev_put() after all device accesses are complete, preventing UAF. The bug can be reproduced by adding mdelay(2000) after linkwatch_do_dev() in __linkwatch_run_queue(), then running: ip tuntap add mode tun name tun_test ip link set tun_test up ip link set tun_test carrier off ip link set tun_test carrier on sleep 0.5 ip tuntap del mode tun name tun_test KASAN report: ================================================================== BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline] BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123 CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: events_unbound linkwatch_event Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline] print_report+0x156/0x4c9 mm/kasan/report.c:482 kasan_report+0xdf/0x1a0 mm/kasan/report.c:595 netdev_need_ops_lock include/net/netdev_lock.h:33 [inline] netdev_unlock_ops include/net/netdev_lock.h:47 [inline] __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245 linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304 process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257 process_scheduled_works kernel/workqueue.c:3340 [inline] worker_thread+0x5da/0xe40 kernel/workqueue.c:3421 kthread+0x3b3/0x730 kernel/kthread.c:463 ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246 </TASK> ==================================================================

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000170000 probability, percentile 0.039420000 (date 2026-04-03)

Problem Types: CWE-416

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All
Operating System Linux Linux Kernel 6.15 - All All
Operating System Linux Linux Kernel 6.15 rc2 All All
Operating System Linux Linux Kernel 6.15 rc3 All All
Operating System Linux Linux Kernel 6.15 rc4 All All
Operating System Linux Linux Kernel 6.15 rc5 All All
Operating System Linux Linux Kernel 6.15 rc6 All All
Operating System Linux Linux Kernel 6.15 rc7 All All
Operating System Linux Linux Kernel 6.19 rc1 All All
Operating System Linux Linux Kernel 6.19 rc2 All All
Operating System Linux Linux Kernel 6.19 rc3 All All
Operating System Linux Linux Kernel 6.19 rc4 All All
Operating System Linux Linux Kernel 6.19 rc5 All All
Operating System Linux Linux Kernel 6.19 rc6 All All
Operating System Linux Linux Kernel 6.19 rc7 All All
Operating System Linux Linux Kernel 6.19 rc8 All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 04efcee6ef8d0f01eef495db047e7216d6e6e38f 2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb git Not specified
CNA Linux Linux affected 04efcee6ef8d0f01eef495db047e7216d6e6e38f 83b67cc9be9223183caf91826d9c194d7fb128fa git Not specified
CNA Linux Linux affected 6.15 Not specified
CNA Linux Linux unaffected 6.15 semver Not specified
CNA Linux Linux unaffected 6.18.10 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/83b67cc9be9223183caf91826d9c194d7fb128fa 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
© CVE.report 2026 |

Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. It is the responsibility of user to evaluate the accuracy, completeness or usefulness of any information, opinion, advice or other content. EACH USER WILL BE SOLELY RESPONSIBLE FOR ANY consequences of his or her direct or indirect use of this web site. ALL WARRANTIES OF ANY KIND ARE EXPRESSLY DISCLAIMED. This site will NOT BE LIABLE FOR ANY DIRECT, INDIRECT or any other kind of loss.

CVE, CWE, and OVAL are registred trademarks of The MITRE Corporation and the authoritative source of CVE content is MITRE's CVE web site. This site includes MITRE data granted under the following license.

CVE.report and Source URL Uptime Status status.cve.report