CVE-2024-42232: libceph: fix race between delayed_work() and ceph_monc_stop()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-08-07 · updated 2026-08-04
Weakness: CWE-416

Description

In the Linux kernel, the following vulnerability has been resolved: libceph: fix race between delayed_work() and ceph_monc_stop() The way the delayed work is handled in ceph_monc_stop() is prone to races with mon_fault() and possibly also finish_hunting(). Both of these can requeue the delayed work which wouldn't be canceled by any of the following code in case that happens after cancel_delayed_work_sync() runs -- __close_session() doesn't mess with the delayed work in order to avoid interfering with the hunting interval logic. This part was missed in commit b5d91704f53e ("libceph: behave in mon_fault() if cur_mon < 0") and use-after-free can still ensue on monc and objects that hang off of it, with monc->auth and monc->monmap being particularly susceptible to quickly being reused. To fix this: - clear monc->cur_mon and monc->hunting as part of closing the session in ceph_monc_stop() - bail from delayed_work() if monc->cur_mon is cleared, similar to how it's done in mon_fault() and finish_hunting() (based on monc->hunting) - call cancel_delayed_work_sync() after the session is closed

Affected products

Linux kernel: before 4.19.318; from 4.20 before 5.4.280; from 5.5 before 5.10.222; from 5.11 before 5.15.163; from 5.16 before 6.1.100; from 6.2 before 6.6.41 — fixed in 4.19.318, 5.10.222, 5.15.163, 5.4.280, 6.1.100, 6.6.41

How to fix

Upgrade to a fixed version: Linux kernel 4.19.318, 5.10.222, 5.15.163, 5.4.280. Check the vendor advisory for mitigations.

References

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