Commit ff58bbc7 authored Jun 16, 2020 by Takashi Iwai

ALSA: usb-audio: Fix potential use-after-free of streams

With the recent full-duplex support of implicit feedback streams, an
endpoint can be still running after closing the capture stream as long
as the playback stream with the sync-endpoint is running. In such a
state, the URBs are still be handled and they may call retire_data_urb
callback, which tries to transfer the data from the PCM buffer. Since
the PCM stream gets closed, this may lead to use-after-free.

This patch adds the proper clearance of the callback at stopping the
capture stream for addressing the possible UAF above.

Fixes: 10ce77e4 ("ALSA: usb-audio: Add duplex sound support for USB devices using implicit feedback")
Link: https://lore.kernel.org/r/20200616120921.12249-1-tiwai@suse.de

Signed-off-by: Takashi Iwai <tiwai@suse.de>

parent a0b03952

sound/usb/pcm.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1787,6 +1787,7 @@ static int snd_usb_substream_capture_trigger(struct snd_pcm_substream *substream
		return 0;
		case SNDRV_PCM_TRIGGER_STOP:
		stop_endpoints(subs);
		subs->data_endpoint->retire_data_urb = NULL;
		subs->running = 0;
		return 0;
		case SNDRV_PCM_TRIGGER_PAUSE_PUSH:

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