CVE-2025-39945 (GCVE-0-2025-39945)
Vulnerability from cvelistv5
Published
2025-10-04 07:31
Modified
2025-10-04 07:37
Severity ?
VLAI Severity ?
EPSS score ?
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
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 Version: fdf24086f4752aee5dfb40143c736250df017820 |
||
{
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{
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{
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{
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}
],
"cpeApplicability": [
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"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."
}
],
"providerMetadata": {
"dateUpdated": "2025-10-04T07:37:04.574Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/fde6e73189f40ebcf0633aed2b68e731c25f3aa3"
},
{
"url": "https://git.kernel.org/stable/c/7b6a5b0a6b392263c3767fc945b311ea04b34bbd"
},
{
"url": "https://git.kernel.org/stable/c/0405055930264ea8fd26f4131466fa7652e5e47d"
},
{
"url": "https://git.kernel.org/stable/c/e1fcd4a9c09feac0902a65615e866dbf22616125"
},
{
"url": "https://git.kernel.org/stable/c/8eeb2091e72d75df8ceaa2172638d61b4cf8929a"
},
{
"url": "https://git.kernel.org/stable/c/6e33a7eed587062ca8161ad1f4584882a860d697"
},
{
"url": "https://git.kernel.org/stable/c/0627e1481676669cae2df0d85b5ff13e7d24c390"
},
{
"url": "https://git.kernel.org/stable/c/cfa7d9b1e3a8604afc84e9e51d789c29574fb216"
}
],
"title": "cnic: Fix use-after-free bugs in cnic_delete_task",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-39945",
"datePublished": "2025-10-04T07:31:07.109Z",
"dateReserved": "2025-04-16T07:20:57.148Z",
"dateUpdated": "2025-10-04T07:37:04.574Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2025-39945\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-04T08:15:47.613\",\"lastModified\":\"2025-10-06T14:56:47.823\",\"vulnStatus\":\"Awaiting Analysis\",\"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.\"}],\"metrics\":{},\"references\":[{\"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\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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