CVE-2026-64424

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: netpoll: fix a use-after-free on shutdown path There is a use-after-free error on netpoll, which is clearly detected by KASAN. BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80 Read of size 1 at addr ... by task kworker/9:1 Workqueue: events queue_process Call Trace: skb_dequeue+0x1e/0xb0 queue_process+0x2c/0x600 process_scheduled_works+0x4b6/0x850 worker_thread+0x414/0x5a0 Allocated by task 242: __netpoll_setup+0x201/0x4a0 netpoll_setup+0x249/0x550 enabled_store+0x32f/0x380 Freed by task 0: kfree+0x1b7/0x540 rcu_core+0x3f8/0x7a0 The problem happens when there is a pending TX worker running in parallel with the cleanup path. This is what happens on netpoll shutdown path: 1) __netpoll_cleanup() is called 2) set dev->npinfo to NULL 3) call_rcu() with rcu_cleanup_netpoll_info() 3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with cancel_delayed_work(), but doesn't wait for the worker to finish 4) and kfree(npinfo); Because 3.1) doesn't really cancel the work, as the comment says "we can't call cancel_delayed_work_sync here, as we are in softirq", the TX worker can run after 4). Tl;DR: queue_process() is not an RCU reader, it reaches npinfo through the work item via container_of(). Use disable_delayed_work_sync() to ensure the worker is completely stopped and prevent any future re-arming attempts. Once npinfo is set to NULL, senders will bail out and not queue new work. The disable flag ensures any in-flight re-arming attempts also fail silently. In the future, we can do the cleanup inline here without needing the npinfo->rcu rcu_head, but that is net-next material.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Modified

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-07-25 10:17:26.483000

Last modified

2026-10-30 13:19:36.340000

View original CVE JSON

{
  "id": "CVE-2026-64424",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-07-25T10:17:26.483",
  "lastModified": "2026-10-30T13:19:36.340",
  "vulnStatus": "Modified",
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      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetpoll: fix a use-after-free on shutdown path\n\nThere is a use-after-free error on netpoll, which is clearly detected by\nKASAN.\n\n      BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x3b/0x80\n      Read of size 1 at addr ... by task kworker/9:1\n      Workqueue: events queue_process\n      Call Trace:\n       skb_dequeue+0x1e/0xb0\n       queue_process+0x2c/0x600\n       process_scheduled_works+0x4b6/0x850\n       worker_thread+0x414/0x5a0\n      Allocated by task 242:\n       __netpoll_setup+0x201/0x4a0\n       netpoll_setup+0x249/0x550\n       enabled_store+0x32f/0x380\n      Freed by task 0:\n       kfree+0x1b7/0x540\n       rcu_core+0x3f8/0x7a0\n\nThe problem happens when there is a pending TX worker running in\nparallel with the cleanup path.\n\nThis is what happens on netpoll shutdown path:\n\n1) __netpoll_cleanup() is called\n2) set dev->npinfo to NULL\n3) call_rcu() with rcu_cleanup_netpoll_info()\n  3.1) rcu_cleanup_netpoll_info() tries to cancel all workers with\n       cancel_delayed_work(), but doesn't wait for the worker to finish\n4) and kfree(npinfo);\n\nBecause 3.1) doesn't really cancel the work, as the comment says \"we\ncan't call cancel_delayed_work_sync here, as we are in softirq\", the TX\nworker can run after 4).\n\nTl;DR: queue_process() is not an RCU reader, it reaches npinfo through\nthe work item via container_of().\n\nUse disable_delayed_work_sync() to ensure the worker is completely\nstopped and prevent any future re-arming attempts. Once npinfo is set\nto NULL, senders will bail out and not queue new work. The disable flag\nensures any in-flight re-arming attempts also fail silently.\n\nIn the future, we can do the cleanup inline here without needing the\nnpinfo->rcu rcu_head, but that is net-next material."
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          "scope": "UNCHANGED",
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