fkie_cve-2025-39945
Vulnerability from fkie_nvd
Published
2025-10-04 08:15
Modified
2025-10-06 14:56
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: cnic: Fix use-after-free bugs in cnic_delete_task The original code uses cancel_delayed_work() in cnic_cm_stop_bnx2x_hw(), which does not guarantee that the delayed work item 'delete_task' has fully completed if it was already running. Additionally, the delayed work item is cyclic, the flush_workqueue() in cnic_cm_stop_bnx2x_hw() only blocks and waits for work items that were already queued to the workqueue prior to its invocation. Any work items submitted after flush_workqueue() is called are not included in the set of tasks that the flush operation awaits. This means that after the cyclic work items have finished executing, a delayed work item may still exist in the workqueue. This leads to use-after-free scenarios where the cnic_dev is deallocated by cnic_free_dev(), while delete_task remains active and attempt to dereference cnic_dev in cnic_delete_task(). A typical race condition is illustrated below: CPU 0 (cleanup) | CPU 1 (delayed work callback) cnic_netdev_event() | cnic_stop_hw() | cnic_delete_task() cnic_cm_stop_bnx2x_hw() | ... cancel_delayed_work() | /* the queue_delayed_work() flush_workqueue() | executes after flush_workqueue()*/ | queue_delayed_work() cnic_free_dev(dev)//free | cnic_delete_task() //new instance | dev = cp->dev; //use Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the cyclic delayed work item is properly canceled and that any ongoing execution of the work item completes before the cnic_dev is deallocated. Furthermore, since cancel_delayed_work_sync() uses __flush_work(work, true) to synchronously wait for any currently executing instance of the work item to finish, the flush_workqueue() becomes redundant and should be removed. This bug was identified through static analysis. To reproduce the issue and validate the fix, I simulated the cnic PCI device in QEMU and introduced intentional delays — such as inserting calls to ssleep() within the cnic_delete_task() function — to increase the likelihood of triggering the bug.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0405055930264ea8fd26f4131466fa7652e5e47d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0627e1481676669cae2df0d85b5ff13e7d24c390
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6e33a7eed587062ca8161ad1f4584882a860d697
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7b6a5b0a6b392263c3767fc945b311ea04b34bbd
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8eeb2091e72d75df8ceaa2172638d61b4cf8929a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/cfa7d9b1e3a8604afc84e9e51d789c29574fb216
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e1fcd4a9c09feac0902a65615e866dbf22616125
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fde6e73189f40ebcf0633aed2b68e731c25f3aa3
Impacted products
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncnic: Fix use-after-free bugs in cnic_delete_task\n\nThe original code uses cancel_delayed_work() in cnic_cm_stop_bnx2x_hw(),\nwhich does not guarantee that the delayed work item \u0027delete_task\u0027 has\nfully completed if it was already running. Additionally, the delayed work\nitem is cyclic, the flush_workqueue() in cnic_cm_stop_bnx2x_hw() only\nblocks and waits for work items that were already queued to the\nworkqueue prior to its invocation. Any work items submitted after\nflush_workqueue() is called are not included in the set of tasks that the\nflush operation awaits. This means that after the cyclic work items have\nfinished executing, a delayed work item may still exist in the workqueue.\nThis leads to use-after-free scenarios where the cnic_dev is deallocated\nby cnic_free_dev(), while delete_task remains active and attempt to\ndereference cnic_dev in cnic_delete_task().\n\nA typical race condition is illustrated below:\n\nCPU 0 (cleanup)              | CPU 1 (delayed work callback)\ncnic_netdev_event()          |\n  cnic_stop_hw()             | cnic_delete_task()\n    cnic_cm_stop_bnx2x_hw()  | ...\n      cancel_delayed_work()  | /* the queue_delayed_work()\n      flush_workqueue()      |    executes after flush_workqueue()*/\n                             | queue_delayed_work()\n  cnic_free_dev(dev)//free   | cnic_delete_task() //new instance\n                             |   dev = cp-\u003edev; //use\n\nReplace cancel_delayed_work() with cancel_delayed_work_sync() to ensure\nthat the cyclic delayed work item is properly canceled and that any\nongoing execution of the work item completes before the cnic_dev is\ndeallocated. Furthermore, since cancel_delayed_work_sync() uses\n__flush_work(work, true) to synchronously wait for any currently\nexecuting instance of the work item to finish, the flush_workqueue()\nbecomes redundant and should be removed.\n\nThis bug was identified through static analysis. To reproduce the issue\nand validate the fix, I simulated the cnic PCI device in QEMU and\nintroduced intentional delays \u2014 such as inserting calls to ssleep()\nwithin the cnic_delete_task() function \u2014 to increase the likelihood\nof triggering the bug."
    }
  ],
  "id": "CVE-2025-39945",
  "lastModified": "2025-10-06T14:56:47.823",
  "metrics": {},
  "published": "2025-10-04T08:15:47.613",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0405055930264ea8fd26f4131466fa7652e5e47d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0627e1481676669cae2df0d85b5ff13e7d24c390"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/6e33a7eed587062ca8161ad1f4584882a860d697"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7b6a5b0a6b392263c3767fc945b311ea04b34bbd"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/8eeb2091e72d75df8ceaa2172638d61b4cf8929a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/cfa7d9b1e3a8604afc84e9e51d789c29574fb216"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e1fcd4a9c09feac0902a65615e866dbf22616125"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/fde6e73189f40ebcf0633aed2b68e731c25f3aa3"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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