UBUNTU-CVE-2025-38708
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.
02 / AFFECTED SOFTWARE
Affected packages
11 explicit affected versions
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51 explicit affected versions
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37 explicit affected versions
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37 explicit affected versions
42 explicit affected versions
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38 explicit affected versions
167 explicit affected versions
9 explicit affected versions
11 explicit affected versions
30 explicit affected versions
13 explicit affected versions
78 explicit affected versions
8 explicit affected versions
7 explicit affected versions
121 explicit affected versions
4 explicit affected versions
67 explicit affected versions
1 explicit affected versions
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76 explicit affected versions
67 explicit affected versions
66 explicit affected versions
13 explicit affected versions
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10 explicit affected versions
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36 explicit affected versions
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14 explicit affected versions
4 explicit affected versions
78 explicit affected versions
11 explicit affected versions
1 explicit affected versions
69 explicit affected versions
123 explicit affected versions
10 explicit affected versions
30 explicit affected versions
66 explicit affected versions
12 explicit affected versions
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10 explicit affected versions
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24 explicit affected versions
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10 explicit affected versions
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26 explicit affected versions
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7 explicit affected versions
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32 explicit affected versions
13 explicit affected versions
85 explicit affected versions
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37 explicit affected versions
35 explicit affected versions
18 explicit affected versions
32 explicit affected versions
118 explicit affected versions
64 explicit affected versions
37 explicit affected versions
120 explicit affected versions
13 explicit affected versions
4 explicit affected versions
23 explicit affected versions
43 explicit affected versions
124 explicit affected versions
1 explicit affected versions
1 explicit affected versions
21 explicit affected versions
9 explicit affected versions
16 explicit affected versions
10 explicit affected versions
76 explicit affected versions
39 explicit affected versions
8 explicit affected versions
7 explicit affected versions
12 explicit affected versions
11 explicit affected versions
111 explicit affected versions
7 explicit affected versions
12 explicit affected versions
14 explicit affected versions
10 explicit affected versions
1 explicit affected versions
7 explicit affected versions
9 explicit affected versions
104 explicit affected versions
12 explicit affected versions
105 explicit affected versions
12 explicit affected versions
03 / CONNECTIONS
Connected vulnerabilities
04 / EVIDENCE
Source records
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.
05 / REFERENCES
Further evidence
- https://git.kernel.org/linus/00c9c9628b49e368d140cfa61d7df9b8922ec2a8
- https://git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8
- https://git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5
- https://git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20
- https://git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89
- https://git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575
- https://git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8
- https://git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1
- https://git.kernel.org/stable/c/84ef8dd3238330d1795745ece83b19f0295751bf
- https://git.kernel.org/stable/c/9f53b2433ad248cd3342cc345f56f5c7904bd8c4
- https://ubuntu.com/security/CVE-2025-38708
- https://ubuntu.com/security/notices/USN-7909-1
- https://ubuntu.com/security/notices/USN-7909-2
- https://ubuntu.com/security/notices/USN-7909-3
- https://ubuntu.com/security/notices/USN-7909-4
- https://ubuntu.com/security/notices/USN-7909-5
- https://ubuntu.com/security/notices/USN-7910-1
- https://ubuntu.com/security/notices/USN-7910-2
- https://ubuntu.com/security/notices/USN-7933-1
- https://ubuntu.com/security/notices/USN-7938-1
- https://ubuntu.com/security/notices/USN-8028-1
- https://ubuntu.com/security/notices/USN-8028-2
- https://ubuntu.com/security/notices/USN-8028-3
- https://ubuntu.com/security/notices/USN-8028-4
- https://ubuntu.com/security/notices/USN-8028-5
- https://ubuntu.com/security/notices/USN-8028-6
- https://ubuntu.com/security/notices/USN-8028-7
- https://ubuntu.com/security/notices/USN-8028-8
- https://ubuntu.com/security/notices/USN-8031-1
- https://ubuntu.com/security/notices/USN-8031-2
- https://ubuntu.com/security/notices/USN-8031-3
- https://ubuntu.com/security/notices/USN-8052-1
- https://ubuntu.com/security/notices/USN-8052-2
- https://ubuntu.com/security/notices/USN-8074-1
- https://ubuntu.com/security/notices/USN-8074-2
- https://ubuntu.com/security/notices/USN-8126-1
- https://www.cve.org/CVERecord?id=CVE-2025-38708