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From:   Xiaomeng Tong <xiam0nd.tong@gmail.com>
To:     oder_chiou@realtek.com, lgirdwood@gmail.com, broonie@kernel.org,
        perex@perex.cz, tiwai@suse.com
Cc:     derek.fang@realtek.com, alsa-devel@alsa-project.org,
        linux-kernel@vger.kernel.org,
        Xiaomeng Tong <xiam0nd.tong@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] codecs: rt5682: fix an incorrect NULL check on list iterator
Date:   Sun, 27 Mar 2022 16:10:02 +0800
Message-Id: <20220327081002.12684-1-xiam0nd.tong@gmail.com>
Precedence: bulk

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@vger.kernel.org
Fixes: ebbfabc16d23d ("ASoC: rt5682: Add CCF usage for providing I2S clks")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@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