CVE-2024-42232

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