Commit 94b98194 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: rawmidi: Take open_mutex around parameter changes 

The input/output parameter changes are pretty intrusive, possibly
involving with the buffer resizing operation.  Hence those should be
performed exclusively; otherwise some ugly race could happen.

This patch puts the existing open_mutex for snd_rawmidi_input_params()
and *_output_params() for protecting the concurrent calls.  Since
those are exported, it's also meant for hardening from the external
calls, too.

Link: https://lore.kernel.org/r/20220617144051.18985-4-tiwai@suse.de


Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent f1d40433

sound/core/rawmidi.c

+25 −14
Original line number Diff line number Diff line
@@ -712,11 +712,19 @@ static int resize_runtime_buffer(struct snd_rawmidi_substream *substream, 
int snd_rawmidi_output_params(struct snd_rawmidi_substream *substream,

			      struct snd_rawmidi_params *params)

{

	if (substream->append && substream->use_count > 1)

		return -EBUSY;

	int err;



	snd_rawmidi_drain_output(substream);

	mutex_lock(&substream->rmidi->open_mutex);

	if (substream->append && substream->use_count > 1)

		err = -EBUSY;

	else

		err = resize_runtime_buffer(substream, params, false);



	if (!err)

		substream->active_sensing = !params->no_active_sensing;

	return resize_runtime_buffer(substream, params, false);

	mutex_unlock(&substream->rmidi->open_mutex);

	return err;

}

EXPORT_SYMBOL(snd_rawmidi_output_params);
@@ -727,19 +735,22 @@ int snd_rawmidi_input_params(struct snd_rawmidi_substream *substream, 
	unsigned int clock_type = params->mode & SNDRV_RAWMIDI_MODE_CLOCK_MASK;

	int err;



	snd_rawmidi_drain_input(substream);

	mutex_lock(&substream->rmidi->open_mutex);

	if (framing == SNDRV_RAWMIDI_MODE_FRAMING_NONE && clock_type != SNDRV_RAWMIDI_MODE_CLOCK_NONE)

		return -EINVAL;

		err = -EINVAL;

	else if (clock_type > SNDRV_RAWMIDI_MODE_CLOCK_MONOTONIC_RAW)

		return -EINVAL;

	if (framing > SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP)

		return -EINVAL;

	snd_rawmidi_drain_input(substream);

		err = -EINVAL;

	else if (framing > SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP)

		err = -EINVAL;

	else

		err = resize_runtime_buffer(substream, params, true);

	if (err < 0)

		return err;



	if (!err) {

		substream->framing = framing;

		substream->clock_type = clock_type;

	}

	mutex_unlock(&substream->rmidi->open_mutex);

	return 0;

}

EXPORT_SYMBOL(snd_rawmidi_input_params);