linux-kernel - [PATCH] sound: soc: samsung: dma.c: Fix for possible null pointer dereference

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Message-Id: <1400535443-5886-1-git-send-email-rickard_strandqvist@spectrumdigital.se>
Date:	Mon, 19 May 2014 23:37:23 +0200
From:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
To:	Ben Dooks <ben-linux@...ff.org>, Kukjin Kim <kgene.kim@...sung.com>
Cc:	Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>,
	Sangbeom Kim <sbkim73@...sung.com>,
	Liam Girdwood <lgirdwood@...il.com>,
	Mark Brown <broonie@...nel.org>,
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.de>,
	linux-arm-kernel@...ts.infradead.org,
	linux-samsung-soc@...r.kernel.org, alsa-devel@...a-project.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] sound: soc: samsung: dma.c:  Fix for possible null pointer dereference

There is otherwise a risk of a possible null pointer dereference.

Was largely found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@...ctrumdigital.se>
---
 sound/soc/samsung/dma.c |   10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/sound/soc/samsung/dma.c b/sound/soc/samsung/dma.c
index dc09b71..1d9bcaa 100644
--- a/sound/soc/samsung/dma.c
+++ b/sound/soc/samsung/dma.c
@@ -115,17 +115,19 @@ static void dma_enqueue(struct snd_pcm_substream *substream)
 static void audio_buffdone(void *data)
 {
 	struct snd_pcm_substream *substream = data;
-	struct runtime_data *prtd = substream->runtime->private_data;
+	struct runtime_data *prtd = NULL;
 
 	pr_debug("Entered %s\n", __func__);
 
-	if (prtd->state & ST_RUNNING) {
+	if (substream)
+		prtd = substream->runtime->private_data;
+
+	if (prtd && prtd->state & ST_RUNNING) {
 		prtd->dma_pos += prtd->dma_period;
 		if (prtd->dma_pos >= prtd->dma_end)
 			prtd->dma_pos = prtd->dma_start;
 
-		if (substream)
-			snd_pcm_period_elapsed(substream);
+		snd_pcm_period_elapsed(substream);
 
 		spin_lock(&prtd->lock);
 		if (!samsung_dma_has_circular()) {
-- 
1.7.10.4

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