| From 0665886ad1392e6b5bae85d7a6ccbed48dca1522 Mon Sep 17 00:00:00 2001 |
| From: Takashi Iwai <tiwai@suse.de> |
| Date: Wed, 20 Apr 2022 15:02:47 +0200 |
| Subject: ALSA: usb-audio: Clear MIDI port active flag after draining |
| |
| From: Takashi Iwai <tiwai@suse.de> |
| |
| commit 0665886ad1392e6b5bae85d7a6ccbed48dca1522 upstream. |
| |
| When a rawmidi output stream is closed, it calls the drain at first, |
| then does trigger-off only when the drain returns -ERESTARTSYS as a |
| fallback. It implies that each driver should turn off the stream |
| properly after the drain. Meanwhile, USB-audio MIDI interface didn't |
| change the port->active flag after the drain. This may leave the |
| output work picking up the port that is closed right now, which |
| eventually leads to a use-after-free for the already released rawmidi |
| object. |
| |
| This patch fixes the bug by properly clearing the port->active flag |
| after the output drain. |
| |
| Reported-by: syzbot+70e777a39907d6d5fd0a@syzkaller.appspotmail.com |
| Cc: <stable@vger.kernel.org> |
| Link: https://lore.kernel.org/r/00000000000011555605dceaff03@google.com |
| Link: https://lore.kernel.org/r/20220420130247.22062-1-tiwai@suse.de |
| Signed-off-by: Takashi Iwai <tiwai@suse.de> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| sound/usb/midi.c | 1 + |
| 1 file changed, 1 insertion(+) |
| |
| --- a/sound/usb/midi.c |
| +++ b/sound/usb/midi.c |
| @@ -1210,6 +1210,7 @@ static void snd_usbmidi_output_drain(str |
| } while (drain_urbs && timeout); |
| finish_wait(&ep->drain_wait, &wait); |
| } |
| + port->active = 0; |
| spin_unlock_irq(&ep->buffer_lock); |
| } |
| |
