fkie_cve-2025-38708
Vulnerability from fkie_nvd
Published
2025-09-04 16:15
Modified
2025-09-05 17:47
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
drbd: add missing kref_get in handle_write_conflicts
With `two-primaries` enabled, DRBD tries to detect "concurrent" writes
and handle write conflicts, so that even if you write to the same sector
simultaneously on both nodes, they end up with the identical data once
the writes are completed.
In handling "superseeded" writes, we forgot a kref_get,
resulting in a premature drbd_destroy_device and use after free,
and further to kernel crashes with symptoms.
Relevance: No one should use DRBD as a random data generator, and apparently
all users of "two-primaries" handle concurrent writes correctly on layer up.
That is cluster file systems use some distributed lock manager,
and live migration in virtualization environments stops writes on one node
before starting writes on the other node.
Which means that other than for "test cases",
this code path is never taken in real life.
FYI, in DRBD 9, things are handled differently nowadays. We still detect
"write conflicts", but no longer try to be smart about them.
We decided to disconnect hard instead: upper layers must not submit concurrent
writes. If they do, that's their fault.
References
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ndrbd: add missing kref_get in handle_write_conflicts\n\nWith `two-primaries` enabled, DRBD tries to detect \"concurrent\" writes\nand handle write conflicts, so that even if you write to the same sector\nsimultaneously on both nodes, they end up with the identical data once\nthe writes are completed.\n\nIn handling \"superseeded\" writes, we forgot a kref_get,\nresulting in a premature drbd_destroy_device and use after free,\nand further to kernel crashes with symptoms.\n\nRelevance: No one should use DRBD as a random data generator, and apparently\nall users of \"two-primaries\" handle concurrent writes correctly on layer up.\nThat is cluster file systems use some distributed lock manager,\nand live migration in virtualization environments stops writes on one node\nbefore starting writes on the other node.\n\nWhich means that other than for \"test cases\",\nthis code path is never taken in real life.\n\nFYI, in DRBD 9, things are handled differently nowadays. We still detect\n\"write conflicts\", but no longer try to be smart about them.\nWe decided to disconnect hard instead: upper layers must not submit concurrent\nwrites. If they do, that\u0027s their fault."
}
],
"id": "CVE-2025-38708",
"lastModified": "2025-09-05T17:47:24.833",
"metrics": {},
"published": "2025-09-04T16:15:39.847",
"references": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/84ef8dd3238330d1795745ece83b19f0295751bf"
},
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"url": "https://git.kernel.org/stable/c/9f53b2433ad248cd3342cc345f56f5c7904bd8c4"
}
],
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"vulnStatus": "Awaiting Analysis"
}
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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.
- 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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