libceph: fix race between delayed_work() and ceph_monc_stop()

Summary

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

Timeline

1. Aug 7, 2024, 3:14 PM UTCCVE published
2. Sep 10, 2024, 4:14 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Aug 5, 2026, 11:35 AM UTCRecord last updated

Affected versions

• Linux Linux

  Version range not reported

• Linux Linux

  4.6

References 8