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 wouldnt be canceled by any of the following code in case that happens after cancel_delayed_work_sync() runs – __close_session() doesnt 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 its done in mon_fault() and finish_hunting() (based on monc->hunting)
• call cancel_delayed_work_sync() after the session is closed

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/1177afeca833174ba83504688eec898c6214f4bf
• https://git.kernel.org/stable/c/20cf67dcb7db842f941eff1af6ee5e9dc41796d7
• https://git.kernel.org/stable/c/2d33654d40a05afd91ab24c9a73ab512a0670a9a
• https://git.kernel.org/stable/c/33d38c5da17f8db2d80e811b7829d2822c10625e
• https://git.kernel.org/stable/c/34b76d1922e41da1fa73d43b764cddd82ac9733c
• https://git.kernel.org/stable/c/63e5d035e3a7ab7412a008f202633c5e6a0a28ea
• https://git.kernel.org/stable/c/69c7b2fe4c9cc1d3b1186d1c5606627ecf0de883
• https://git.kernel.org/stable/c/9525af1f58f67df387768770fcf6d6a8f23aee3d