[PATCH 5.4 148/215] ALSA: line6: Sync the pending work cancel at disconnection

[Greg Kroah-Hartman]

From: Takashi Iwai <tiwai@xxxxxxx>

commit 68359a1ad8447c99732ebeab8c169bfed543667a upstream.

Recently syzkaller reported a UAF in LINE6 driver, and it's likely
because we call cancel_delayed_work() at the disconnect callback
instead of cancel_delayed_work_sync().  Let's use the correct one
instead.

Reported-by: syzbot+145012a46658ac00fc9e@xxxxxxxxxxxxxxxxxxxxxxxxx
Suggested-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/s5hlfjr4gio.wl-tiwai@xxxxxxx
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 sound/usb/line6/driver.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/sound/usb/line6/driver.c
+++ b/sound/usb/line6/driver.c
@@ -820,7 +820,7 @@ void line6_disconnect(struct usb_interfa
 	if (WARN_ON(usbdev != line6->usbdev))
 		return;
 
-	cancel_delayed_work(&line6->startup_work);
+	cancel_delayed_work_sync(&line6->startup_work);
 
 	if (line6->urb_listen != NULL)
 		line6_stop_listen(line6);