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CriticalFix available

drbd: add missing kref_get in handle_write_conflicts

Type: advisorySources: OSV

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.

Products
Kernel
Affected versions
Not specified
Fixed versions
5.10.241, 5.15.190, 5.4.297, 6.1.149, 6.12.43, 6.15.11, 6.16.2, 6.6.103
CVEs
CVE-2025-38708
Confirmed fixed CVEs
Not specified
Updated in this feed
4 Nov 2026, 21:26 UTC · Revision 1

Source evidence

drbd: add missing kref_get in handle_write_conflicts

core-osv · Original source

Published 4 Sept 2025, 15:32 UTC

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.

osv:CVE-2025-38708

Kernel

Fixed versions: 5.4.297, 5.10.241, 5.15.190, 6.1.149, 6.6.103, 6.12.43, 6.15.11, 6.16.2

Complete source record
{
  "id": "913f817ff53507f556519fb1ddf69001613b97549f4cdeee9c046cb1588d9fa8",
  "url": "https://osv.dev/vulnerability/CVE-2025-38708",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "drbd: add missing kref_get in handle_write_conflicts",
    "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.",
    "evidence": "osv:CVE-2025-38708",
    "products": [
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        "name": {
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          "evidence": "/affected/1/package/name"
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        "prerequisites": [],
        "fixed_versions": [
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            "evidence": "/affected/1/ranges"
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          {
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        {
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              "type": "ECOSYSTEM",
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                  "introduced": "4.5.0"
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          "package": {
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      ],
      "modified": "2026-10-28T02:30:39.637818644Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-032379.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8",
        "https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5",
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        "https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1",
        "https://git.kernel.org/stable/c/84ef8dd3238330d1795745ece83b19f0295751bf",
        "https://git.kernel.org/stable/c/9f53b2433ad248cd3342cc345f56f5c7904bd8c4",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html",
        "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38708.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2025-38708",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/38xxx/CVE-2025-38708.json"
      }
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    "related_cves": [
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 507252,
  "published_at": "2025-09-04T15:32:59.108+00:00"
}