Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: md/md-llbitmap: stop daemon timer rearm on destroy llbitmap_destroy() deletes pending_timer before flushing md_llbitmap_io_wq. However, daemon_work can still be queued or running after the timer has been deleted, and the daemon path can arm pending_timer again when it finds dirty chunks that are not ready to flush yet. If that happens during teardown, pending_timer can remain armed after llbitmap is freed and later dereference freed memory. Add a BITMAP_SHUTDOWN bit to llbitmap->flags, set it before deleting the timer, and make the timer and daemon paths stop queueing or rearming work once teardown starts. Cancel daemon_work before flushing the shared workqueue so no already queued daemon instance can race with the free. Use timer_shutdown_sync() so a daemon instance that passed the shutdown check before teardown cannot rearm the timer afterward. BITMAP_SHUTDOWN is a runtime-only state. Mask it out when reading and updating the llbitmap superblock so the shutdown state is never loaded from disk or persisted to disk.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected 5ab829f1971dc99f2aac10846c378e67fc875abc before c55aa6c17f019b6296952d336939891efa084c06; affected 5ab829f1971dc99f2aac10846c378e67fc875abc before bb7f92d58fca9a9f06f3f51a82481c5f0bbbd46c; affected 5ab829f1971dc99f2aac10846c378e67fc875abc before 5553d64e01d9a995be6c3de38501c6dd4ceede3b |
| Linux / Linux | affected 6.18; unaffected 0 before 6.18; unaffected 6.18.52 through 6.18.*; unaffected 7.2.6 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.