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Commit f9d20283 authored by Takashi Iwai's avatar Takashi Iwai
Browse files

ALSA: rawmidi - Fix possible race in open 



The module refcount should be handled in the register_mutex to avoid
possible races with module unloading.

Signed-off-by: default avatarTakashi Iwai <tiwai@suse.de>
parent fec6c6fe

sound/core/rawmidi.c

+7 −7
Original line number Diff line number Diff line
@@ -237,15 +237,16 @@ int snd_rawmidi_kernel_open(struct snd_card *card, int device, int subdevice, 
		rfile->input = rfile->output = NULL;

	mutex_lock(&register_mutex);

	rmidi = snd_rawmidi_search(card, device);

	mutex_unlock(&register_mutex);

	if (rmidi == NULL) {

		err = -ENODEV;

		goto __error1;

		mutex_unlock(&register_mutex);

		return -ENODEV;

	}

	if (!try_module_get(rmidi->card->module)) {

		err = -EFAULT;

		goto __error1;

		mutex_unlock(&register_mutex);

		return -ENXIO;

	}

	mutex_unlock(&register_mutex);



	if (!(mode & SNDRV_RAWMIDI_LFLG_NOOPENLOCK))

		mutex_lock(&rmidi->open_mutex);

	if (mode & SNDRV_RAWMIDI_LFLG_INPUT) {
@@ -370,10 +371,9 @@ int snd_rawmidi_kernel_open(struct snd_card *card, int device, int subdevice, 
		snd_rawmidi_runtime_free(sinput);

	if (output != NULL)

		snd_rawmidi_runtime_free(soutput);

	module_put(rmidi->card->module);

	if (!(mode & SNDRV_RAWMIDI_LFLG_NOOPENLOCK))

		mutex_unlock(&rmidi->open_mutex);

      __error1:

	module_put(rmidi->card->module);

	return err;

}