CVE-2025-38708

01/Description

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 products

linux: linux kernel; debian: debian linux

03/References10

• git.kernel.org/stable/c/00c9c9628b49e368d140cfa61d7df9b8922ec2a8 Patch
• git.kernel.org/stable/c/0336bfe9c237476bd7c45605a36ca79c2bca62e5 Patch
• git.kernel.org/stable/c/3a896498f6f577e57bf26aaa93b48c22b6d20c20 Patch
• git.kernel.org/stable/c/46e3763dcae0ffcf8fcfaff4fc10a90a92ffdd89 Patch
• git.kernel.org/stable/c/57418de35420cedab035aa1da8a26c0499b7f575 Patch
• git.kernel.org/stable/c/7d483ad300fc0a06f69b019dda8f74970714baf8 Patch
• git.kernel.org/stable/c/810cd546a29bfac90ed1328ea01d693d4bd11cb1 Patch
• git.kernel.org/stable/c/84ef8dd3238330d1795745ece83b19f0295751bf Patch
• git.kernel.org/stable/c/9f53b2433ad248cd3342cc345f56f5c7904bd8c4 Patch
• lists.debian.org/debian-lts-announce/2025/10/msg00007.html Mailing ListThird Party Advisory