[PATCH] codecs: rt5682: fix an incorrect NULL check on list iterator

[Xiaomeng Tong]

The bug is here:
	if (!dai) {

The list iterator value 'dai' will *always* be set and non-NULL
by for_each_component_dais(), so it is incorrect to assume that
the iterator value will be NULL if the list is empty or no element
is found (In fact, it will be a bogus pointer to an invalid struct
object containing the HEAD). Otherwise it will bypass the check
'if (!dai) {' (never call dev_err() and never return -ENODEV;)
and lead to invalid memory access lately when calling
'rt5682_set_bclk1_ratio(dai, factor);'.

To fix the bug, just return rt5682_set_bclk1_ratio(dai, factor);
when found the 'dai', otherwise dev_err() and return -ENODEV;

Cc: stable at vger.kernel.org
Fixes: ebbfabc16d23d ("ASoC: rt5682: Add CCF usage for providing I2S clks")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong at gmail.com>
---
 sound/soc/codecs/rt5682.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/rt5682.c b/sound/soc/codecs/rt5682.c
index be68d573a490..c9ff9c89adf7 100644
--- a/sound/soc/codecs/rt5682.c
+++ b/sound/soc/codecs/rt5682.c
@@ -2822,14 +2822,11 @@ static int rt5682_bclk_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	for_each_component_dais(component, dai)
 		if (dai->id == RT5682_AIF1)
-			break;
-	if (!dai) {
-		dev_err(rt5682->i2c_dev, "dai %d not found in component\n",
-			RT5682_AIF1);
-		return -ENODEV;
-	}
+			return rt5682_set_bclk1_ratio(dai, factor);
 
-	return rt5682_set_bclk1_ratio(dai, factor);
+	dev_err(rt5682->i2c_dev, "dai %d not found in component\n",
+		RT5682_AIF1);
+	return -ENODEV;
 }
 
 static const struct clk_ops rt5682_dai_clk_ops[RT5682_DAI_NUM_CLKS] = {
-- 
2.17.1