usb: typec: ucsi: Fix NULL pointer dereference

Making sure the UCSI debugfs entry actually exists before
attempting to remove it.

Fixes: df0383f ("usb: typec: ucsi: Add debugfs for ucsi commands")
Reported-by: Dave Hansen <[email protected]>
Closes: https://lore.kernel.org/linux-usb/[email protected]/
Suggested-by: Dave Hansen <[email protected]>
Suggested-by: Mario Limonciello <[email protected]>
Cc: Saranya Gopal <[email protected]>
Signed-off-by: Heikki Krogerus <[email protected]>
Cc: Thorsten Leemhuis <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Greg Kroah-Hartman <[email protected]>

Author: Heikki Krogerus

drivers/usb/typec/ucsi/debugfs.c

@@ -84,6 +84,9 @@ void ucsi_debugfs_register(struct ucsi *ucsi)
 
 void ucsi_debugfs_unregister(struct ucsi *ucsi)
 {
+	if (IS_ERR_OR_NULL(ucsi) || !ucsi->debugfs)
+		return;
+
 	debugfs_remove_recursive(ucsi->debugfs->dentry);
 	kfree(ucsi->debugfs);
 }