CVE-2026-23192 (GCVE-0-2026-23192)

Vulnerability from cvelistv5 – Published: 2026-02-14 16:27 – Updated: 2026-02-14 16:27
VLAI?
Title
linkwatch: use __dev_put() in callers to prevent UAF
Summary
In 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> ==================================================================
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 04efcee6ef8d0f01eef495db047e7216d6e6e38f , < 2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb (git)
Affected: 04efcee6ef8d0f01eef495db047e7216d6e6e38f , < 83b67cc9be9223183caf91826d9c194d7fb128fa (git)
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    Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.10 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/link_watch.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb",
              "status": "affected",
              "version": "04efcee6ef8d0f01eef495db047e7216d6e6e38f",
              "versionType": "git"
            },
            {
              "lessThan": "83b67cc9be9223183caf91826d9c194d7fb128fa",
              "status": "affected",
              "version": "04efcee6ef8d0f01eef495db047e7216d6e6e38f",
              "versionType": "git"
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/link_watch.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
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              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.10",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.10",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlinkwatch: use __dev_put() in callers to prevent UAF\n\nAfter linkwatch_do_dev() calls __dev_put() to release the linkwatch\nreference, the device refcount may drop to 1. At this point,\nnetdev_run_todo() can proceed (since linkwatch_sync_dev() sees an\nempty list and returns without blocking), wait for the refcount to\nbecome 1 via netdev_wait_allrefs_any(), and then free the device\nvia kobject_put().\n\nThis creates a use-after-free when __linkwatch_run_queue() tries to\ncall netdev_unlock_ops() on the already-freed device.\n\nNote that adding netdev_lock_ops()/netdev_unlock_ops() pair in\nnetdev_run_todo() before kobject_put() would not work, because\nnetdev_lock_ops() is conditional - it only locks when\nnetdev_need_ops_lock() returns true. If the device doesn\u0027t require\nops_lock, linkwatch won\u0027t hold any lock, and netdev_run_todo()\nacquiring the lock won\u0027t provide synchronization.\n\nFix this by moving __dev_put() from linkwatch_do_dev() to its\ncallers. The device reference logically pairs with de-listing the\ndevice, so it\u0027s reasonable for the caller that did the de-listing\nto release it. This allows placing __dev_put() after all device\naccesses are complete, preventing UAF.\n\nThe bug can be reproduced by adding mdelay(2000) after\nlinkwatch_do_dev() in __linkwatch_run_queue(), then running:\n\n  ip tuntap add mode tun name tun_test\n  ip link set tun_test up\n  ip link set tun_test carrier off\n  ip link set tun_test carrier on\n  sleep 0.5\n  ip tuntap del mode tun name tun_test\n\nKASAN report:\n\n ==================================================================\n BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123\n\n CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\n Workqueue: events_unbound linkwatch_event\n Call Trace:\n  \u003cTASK\u003e\n  __dump_stack lib/dump_stack.c:94 [inline]\n  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\n  print_address_description mm/kasan/report.c:378 [inline]\n  print_report+0x156/0x4c9 mm/kasan/report.c:482\n  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595\n  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\n  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\n  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\n  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304\n  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257\n  process_scheduled_works kernel/workqueue.c:3340 [inline]\n  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421\n  kthread+0x3b3/0x730 kernel/kthread.c:463\n  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\n  \u003c/TASK\u003e\n =================================================================="
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-14T16:27:19.557Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb"
        },
        {
          "url": "https://git.kernel.org/stable/c/83b67cc9be9223183caf91826d9c194d7fb128fa"
        }
      ],
      "title": "linkwatch: use __dev_put() in callers to prevent UAF",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23192",
    "datePublished": "2026-02-14T16:27:19.557Z",
    "dateReserved": "2026-01-13T15:37:45.985Z",
    "dateUpdated": "2026-02-14T16:27:19.557Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-23192\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-02-14T17:15:57.020\",\"lastModified\":\"2026-02-14T17:15:57.020\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nlinkwatch: use __dev_put() in callers to prevent UAF\\n\\nAfter linkwatch_do_dev() calls __dev_put() to release the linkwatch\\nreference, the device refcount may drop to 1. At this point,\\nnetdev_run_todo() can proceed (since linkwatch_sync_dev() sees an\\nempty list and returns without blocking), wait for the refcount to\\nbecome 1 via netdev_wait_allrefs_any(), and then free the device\\nvia kobject_put().\\n\\nThis creates a use-after-free when __linkwatch_run_queue() tries to\\ncall netdev_unlock_ops() on the already-freed device.\\n\\nNote that adding netdev_lock_ops()/netdev_unlock_ops() pair in\\nnetdev_run_todo() before kobject_put() would not work, because\\nnetdev_lock_ops() is conditional - it only locks when\\nnetdev_need_ops_lock() returns true. If the device doesn\u0027t require\\nops_lock, linkwatch won\u0027t hold any lock, and netdev_run_todo()\\nacquiring the lock won\u0027t provide synchronization.\\n\\nFix this by moving __dev_put() from linkwatch_do_dev() to its\\ncallers. The device reference logically pairs with de-listing the\\ndevice, so it\u0027s reasonable for the caller that did the de-listing\\nto release it. This allows placing __dev_put() after all device\\naccesses are complete, preventing UAF.\\n\\nThe bug can be reproduced by adding mdelay(2000) after\\nlinkwatch_do_dev() in __linkwatch_run_queue(), then running:\\n\\n  ip tuntap add mode tun name tun_test\\n  ip link set tun_test up\\n  ip link set tun_test carrier off\\n  ip link set tun_test carrier on\\n  sleep 0.5\\n  ip tuntap del mode tun name tun_test\\n\\nKASAN report:\\n\\n ==================================================================\\n BUG: KASAN: use-after-free in netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\\n BUG: KASAN: use-after-free in netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\\n BUG: KASAN: use-after-free in __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\\n Read of size 8 at addr ffff88804de5c008 by task kworker/u32:10/8123\\n\\n CPU: 0 UID: 0 PID: 8123 Comm: kworker/u32:10 Not tainted syzkaller #0 PREEMPT(full)\\n Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014\\n Workqueue: events_unbound linkwatch_event\\n Call Trace:\\n  \u003cTASK\u003e\\n  __dump_stack lib/dump_stack.c:94 [inline]\\n  dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120\\n  print_address_description mm/kasan/report.c:378 [inline]\\n  print_report+0x156/0x4c9 mm/kasan/report.c:482\\n  kasan_report+0xdf/0x1a0 mm/kasan/report.c:595\\n  netdev_need_ops_lock include/net/netdev_lock.h:33 [inline]\\n  netdev_unlock_ops include/net/netdev_lock.h:47 [inline]\\n  __linkwatch_run_queue+0x865/0x8a0 net/core/link_watch.c:245\\n  linkwatch_event+0x8f/0xc0 net/core/link_watch.c:304\\n  process_one_work+0x9c2/0x1840 kernel/workqueue.c:3257\\n  process_scheduled_works kernel/workqueue.c:3340 [inline]\\n  worker_thread+0x5da/0xe40 kernel/workqueue.c:3421\\n  kthread+0x3b3/0x730 kernel/kthread.c:463\\n  ret_from_fork+0x754/0xaf0 arch/x86/kernel/process.c:158\\n  ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246\\n  \u003c/TASK\u003e\\n ==================================================================\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2718ae6af7445ba2ee0abf6365ca43a9a3b16aeb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/83b67cc9be9223183caf91826d9c194d7fb128fa\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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