On Tue, 20 Oct 2015 11:46:31 +0200, Lars-Peter Clausen wrote:
Use the new dmaengine_synchronize() function to make sure that all complete callbacks have finished running before the runtime data, which is accessed in the completed callback, is freed.
This fixes a long standing use-after-free race condition that has been observed on some systems.
What if a substream is restarted immediately after the stop?
Takashi
Signed-off-by: Lars-Peter Clausen lars@metafoo.de
sound/core/pcm_dmaengine.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/sound/core/pcm_dmaengine.c b/sound/core/pcm_dmaengine.c index fba365a..697c166 100644 --- a/sound/core/pcm_dmaengine.c +++ b/sound/core/pcm_dmaengine.c @@ -202,13 +202,13 @@ int snd_dmaengine_pcm_trigger(struct snd_pcm_substream *substream, int cmd) if (runtime->info & SNDRV_PCM_INFO_PAUSE) dmaengine_pause(prtd->dma_chan); else
dmaengine_terminate_all(prtd->dma_chan);
dmaengine_terminate_async(prtd->dma_chan);
dmaengine_terminate_all(prtd->dma_chan);
dmaengine_terminate_async(prtd->dma_chan);@@ -346,6 +346,7 @@ int snd_dmaengine_pcm_close(struct snd_pcm_substream *substream) { struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
dmaengine_synchronize(prtd->dma_chan); kfree(prtd);
return 0;
@@ -362,9 +363,11 @@ int snd_dmaengine_pcm_close_release_chan(struct snd_pcm_substream *substream) { struct dmaengine_pcm_runtime_data *prtd = substream_to_prtd(substream);
- dmaengine_synchronize(prtd->dma_chan); dma_release_channel(prtd->dma_chan);
- kfree(prtd);
- return snd_dmaengine_pcm_close(substream);
- return 0;
} EXPORT_SYMBOL_GPL(snd_dmaengine_pcm_close_release_chan);
-- 2.1.4