Messages in this thread Patch in this message | | | From | Daniel THOMPSON <> | Date | Fri, 15 Aug 2008 10:53:38 +0100 | Subject | [PATCH] sound: Fix esoteric double free in the dummy sound driver. |
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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: Daniel R Thompson <daniel.thompson@st.com> --- sound/drivers/dummy.c | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-)
diff --git a/sound/drivers/dummy.c b/sound/drivers/dummy.c index 4e4c69e..90fc1ce 100644 --- a/sound/drivers/dummy.c +++ b/sound/drivers/dummy.c @@ -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; } -- 1.5.5.1
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