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authorTakashi Iwai <tiwai@suse.de>2022-04-20 15:02:47 +0200
committerTakashi Iwai <tiwai@suse.de>2022-04-20 15:13:45 +0200
commit0665886ad1392e6b5bae85d7a6ccbed48dca1522 (patch)
tree9a00a5473e824803beff2336a41ed2d05619a5f1 /sound
parent0aea30a07ec6b50de0fc5f5b2ec34a68ead86b61 (diff)
ALSA: usb-audio: Clear MIDI port active flag after draining
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>
Diffstat (limited to 'sound')
-rw-r--r--sound/usb/midi.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 2c01649c70f6..7c6ca2b433a5 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1194,6 +1194,7 @@ static void snd_usbmidi_output_drain(struct snd_rawmidi_substream *substream)
} while (drain_urbs && timeout);
finish_wait(&ep->drain_wait, &wait);
}
+ port->active = 0;
spin_unlock_irq(&ep->buffer_lock);
}