ASoC: amd: acp: Fix possible UAF in acp_dma_open

[ Upstream commit 3420fdb ]

Smatch report warning as follows:

sound/soc/amd/acp/acp-platform.c:199 acp_dma_open() warn:
  '&stream->list' not removed from list

If snd_pcm_hw_constraint_integer() fails in acp_dma_open(),
stream will be freed, but stream->list will not be removed from
adata->stream_list, then list traversal may cause UAF.

Fix by adding the newly allocated stream to the list once it's fully
initialised.

Fixes: 7929985 ("ASoC: amd: acp: Initialize list to store acp_stream during pcm_open")
Signed-off-by: Gaosheng Cui <cuigaosheng1@huawei.com>
Link: https://lore.kernel.org/r/20221118030056.3135960-1-cuigaosheng1@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

sound/soc/amd/acp/acp-platform.c

@@ -184,10 +184,6 @@ static int acp_dma_open(struct snd_soc_component *component, struct snd_pcm_subs
 
 	stream->substream = substream;
 
-	spin_lock_irq(&adata->acp_lock);
-	list_add_tail(&stream->list, &adata->stream_list);
-	spin_unlock_irq(&adata->acp_lock);
-
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		runtime->hw = acp_pcm_hardware_playback;
 	else
@@ -203,6 +199,10 @@ static int acp_dma_open(struct snd_soc_component *component, struct snd_pcm_subs
 
 	writel(1, ACP_EXTERNAL_INTR_ENB(adata));
 
+	spin_lock_irq(&adata->acp_lock);
+	list_add_tail(&stream->list, &adata->stream_list);
+	spin_unlock_irq(&adata->acp_lock);
+
 	return ret;
 }