In the Linux kernel, the following vulnerability has been resolved: vfio: Remove device debugfs before releasing devres VFIO device debugf

In the Linux kernel, the following vulnerability has been resolved:

vfio: Remove device debugfs before releasing devres

VFIO device debugfs files created with debugfs_create_devm_seqfile()
store a devres allocated debugfs_devm_entry as inode private data.
vfio_unregister_group_dev() currently calls vfio_device_del() before
vfio_device_debugfs_exit(), but device_del() releases devres. This can
leave debugfs entries visible with stale inode private data while
unregister waits for userspace references to drain.

Remove the per-device debugfs tree before vfio_device_del(). The debugfs
view is diagnostic only, so losing it at the start of unregister is
preferable to preserving entries whose backing storage may already have
been released.

Complete the teardown by clearing the per-device debugfs root after
removal. This matches the global debugfs root cleanup and prevents
future users from mistaking a removed dentry for a live debugfs tree
during the remainder of unregister.