CVE-2024-26758

In the Linux kernel, the following vulnerability has been resolved: md:
Don’t ignore suspended array in md_check_recovery() mddev_suspend() never
stop sync_thread, hence it doesn’t make sense to ignore suspended array in
md_check_recovery(), which might cause sync_thread can’t be unregistered.
After commit f52f5c71f3d4 (“md: fix stopping sync thread”), following hang
can be triggered by test shell/integrity-caching.sh: 1) suspend the array:
raid_postsuspend mddev_suspend 2) stop the array: raid_dtr md_stop
__md_stop_writes stop_sync_thread set_bit(MD_RECOVERY_INTR,
&mddev->recovery); md_wakeup_thread_directly(mddev->sync_thread);
wait_event(…, !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) 3) sync
thread done: md_do_sync set_bit(MD_RECOVERY_DONE, &mddev->recovery);
md_wakeup_thread(mddev->thread); 4) daemon thread can’t unregister sync
thread: md_check_recovery if (mddev->suspended) return; -> return directly
md_read_sync_thread clear_bit(MD_RECOVERY_RUNNING, &mddev->recovery); ->
MD_RECOVERY_RUNNING can’t be cleared, hence step 2 hang; This problem is
not just related to dm-raid, fix it by ignoring suspended array in
md_check_recovery(). And follow up patches will improve dm-raid better to
frozen sync thread during suspend.