linux-kernel - [PATCH] codecs: rt5682s: fix an incorrect NULL check on list iterator

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Message-Id: <20220327081300.12962-1-xiam0nd.tong@gmail.com>
Date:   Sun, 27 Mar 2022 16:13:00 +0800
From:   Xiaomeng Tong <xiam0nd.tong@...il.com>
To:     oder_chiou@...ltek.com, lgirdwood@...il.com, broonie@...nel.org,
        perex@...ex.cz, tiwai@...e.com
Cc:     derek.fang@...ltek.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org,
        Xiaomeng Tong <xiam0nd.tong@...il.com>, stable@...r.kernel.org
Subject: [PATCH] codecs: rt5682s: fix an incorrect NULL check on list iterator

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
'rt5682s_set_bclk1_ratio(dai, factor);'.

To fix the bug, just return rt5682s_set_bclk1_ratio(dai, factor);
when found the 'dai', otherwise dev_err() and return -ENODEV;

Cc: stable@...r.kernel.org
Fixes: bdd229ab26be9 ("ASoC: rt5682s: Add driver for ALC5682I-VS codec")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@...il.com>
---
 sound/soc/codecs/rt5682s.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/rt5682s.c b/sound/soc/codecs/rt5682s.c
index 1e662d1be2b3..c890e51ff953 100644
--- a/sound/soc/codecs/rt5682s.c
+++ b/sound/soc/codecs/rt5682s.c
@@ -2686,14 +2686,11 @@ static int rt5682s_bclk_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	for_each_component_dais(component, dai)
 		if (dai->id == RT5682S_AIF1)
-			break;
-	if (!dai) {
-		dev_err(component->dev, "dai %d not found in component\n",
-			RT5682S_AIF1);
-		return -ENODEV;
-	}
+			return rt5682s_set_bclk1_ratio(dai, factor);
 
-	return rt5682s_set_bclk1_ratio(dai, factor);
+	dev_err(component->dev, "dai %d not found in component\n",
+		RT5682S_AIF1);
+	return -ENODEV;
 }
 
 static const struct clk_ops rt5682s_dai_clk_ops[RT5682S_DAI_NUM_CLKS] = {
-- 
2.17.1