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Commit 54e8e21e authored by Daniel THOMPSON's avatar Daniel THOMPSON Committed by Jaroslav Kysela
Browse files

sound: Fix esoteric double free in the dummy sound driver. 



The dummy driver uses runtime->private_free but still frees
its pcm structures on error paths.

This is esoteric because the error paths in question are
unreachable. Thus the bug is only a problem when someone
copies this code into other drivers.

Signed-off-by: default avatarDaniel R Thompson <daniel.thompson@st.com>
Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
parent 8daaaa97

sound/drivers/dummy.c

+4 −6
Original line number Diff line number Diff line
@@ -354,6 +354,7 @@ static int snd_card_dummy_playback_open(struct snd_pcm_substream *substream) 
	if ((dpcm = new_pcm_stream(substream)) == NULL)

		return -ENOMEM;

	runtime->private_data = dpcm;

	/* makes the infrastructure responsible for freeing dpcm */

	runtime->private_free = snd_card_dummy_runtime_free;

	runtime->hw = snd_card_dummy_playback;

	if (substream->pcm->device & 1) {
@@ -362,10 +363,8 @@ static int snd_card_dummy_playback_open(struct snd_pcm_substream *substream) 
	}

	if (substream->pcm->device & 2)

		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);

	if ((err = add_playback_constraints(runtime)) < 0) {

		kfree(dpcm);

	if ((err = add_playback_constraints(runtime)) < 0)

		return err;

	}



	return 0;

}
@@ -379,6 +378,7 @@ static int snd_card_dummy_capture_open(struct snd_pcm_substream *substream) 
	if ((dpcm = new_pcm_stream(substream)) == NULL)

		return -ENOMEM;

	runtime->private_data = dpcm;

	/* makes the infrastructure responsible for freeing dpcm */

	runtime->private_free = snd_card_dummy_runtime_free;

	runtime->hw = snd_card_dummy_capture;

	if (substream->pcm->device == 1) {
@@ -387,10 +387,8 @@ static int snd_card_dummy_capture_open(struct snd_pcm_substream *substream) 
	}

	if (substream->pcm->device & 2)

		runtime->hw.info &= ~(SNDRV_PCM_INFO_MMAP|SNDRV_PCM_INFO_MMAP_VALID);

	if ((err = add_capture_constraints(runtime)) < 0) {

		kfree(dpcm);

	if ((err = add_capture_constraints(runtime)) < 0)

		return err;

	}



	return 0;

}