In the Linux kernel, the following vulnerability has been resolved:
nbd: fix uaf in nbd_open
Commit 4af5f2e03013 ("nbd: use blkmqallocdisk and blkcleanupdisk") cleans up disk by blkcleanupdisk() and it won't set disk->privatedata as NULL as before. UAF may be triggered in nbdopen() if someone tries to open nbd device right after nbdput() since nbd has been free in nbddevremove().
Fix this by implementing ->free_disk and free private data in it.