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.
Signed-off-by: Takashi Iwai tiwai@suse.de --- sound/core/rawmidi.c | 39 +++++++++++++++++++++++++-------------- 1 file changed, 25 insertions(+), 14 deletions(-)
diff --git a/sound/core/rawmidi.c b/sound/core/rawmidi.c index 0a00f37d8c42..7fd6b369d46f 100644 --- a/sound/core/rawmidi.c +++ b/sound/core/rawmidi.c @@ -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); - substream->active_sensing = !params->no_active_sensing; - return resize_runtime_buffer(substream, params, false); + 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; + 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 = resize_runtime_buffer(substream, params, true); - if (err < 0) - return err; + err = -EINVAL; + else if (framing > SNDRV_RAWMIDI_MODE_FRAMING_TSTAMP) + err = -EINVAL; + else + err = resize_runtime_buffer(substream, params, true);
- substream->framing = framing; - substream->clock_type = clock_type; + if (!err) { + substream->framing = framing; + substream->clock_type = clock_type; + } + mutex_unlock(&substream->rmidi->open_mutex); return 0; } EXPORT_SYMBOL(snd_rawmidi_input_params);