linux-kernel - [PATCH] ASoC: mediatek: common: handle NULL case in suspend/resume function

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Message-ID: <20210902082111.9287-1-trevor.wu@mediatek.com>
Date:   Thu, 2 Sep 2021 16:21:11 +0800
From:   Trevor Wu <trevor.wu@...iatek.com>
To:     <broonie@...nel.org>, <tiwai@...e.com>, <matthias.bgg@...il.com>
CC:     <trevor.wu@...iatek.com>, <alsa-devel@...a-project.org>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <dan.carpenter@...cle.com>,
        <bicycle.tsai@...iatek.com>
Subject: [PATCH] ASoC: mediatek: common: handle NULL case in suspend/resume function

When memory allocation for afe->reg_back_up fails, reg_back_up can't
be used.
Keep the suspend/resume flow but skip register backup when
afe->reg_back_up is NULL, in case illegal memory access happens.

Fixes: 283b612429a2 ("ASoC: mediatek: implement mediatek common structure")
Signed-off-by: Trevor Wu <trevor.wu@...iatek.com>
---
 sound/soc/mediatek/common/mtk-afe-fe-dai.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/sound/soc/mediatek/common/mtk-afe-fe-dai.c b/sound/soc/mediatek/common/mtk-afe-fe-dai.c
index baaa5881b1d4..e95c7c018e7d 100644
--- a/sound/soc/mediatek/common/mtk-afe-fe-dai.c
+++ b/sound/soc/mediatek/common/mtk-afe-fe-dai.c
@@ -334,9 +334,11 @@ int mtk_afe_suspend(struct snd_soc_component *component)
 			devm_kcalloc(dev, afe->reg_back_up_list_num,
 				     sizeof(unsigned int), GFP_KERNEL);
 
-	for (i = 0; i < afe->reg_back_up_list_num; i++)
-		regmap_read(regmap, afe->reg_back_up_list[i],
-			    &afe->reg_back_up[i]);
+	if (afe->reg_back_up) {
+		for (i = 0; i < afe->reg_back_up_list_num; i++)
+			regmap_read(regmap, afe->reg_back_up_list[i],
+				    &afe->reg_back_up[i]);
+	}
 
 	afe->suspended = true;
 	afe->runtime_suspend(dev);
@@ -356,12 +358,13 @@ int mtk_afe_resume(struct snd_soc_component *component)
 
 	afe->runtime_resume(dev);
 
-	if (!afe->reg_back_up)
+	if (!afe->reg_back_up) {
 		dev_dbg(dev, "%s no reg_backup\n", __func__);
-
-	for (i = 0; i < afe->reg_back_up_list_num; i++)
-		mtk_regmap_write(regmap, afe->reg_back_up_list[i],
-				 afe->reg_back_up[i]);
+	} else {
+		for (i = 0; i < afe->reg_back_up_list_num; i++)
+			mtk_regmap_write(regmap, afe->reg_back_up_list[i],
+					 afe->reg_back_up[i]);
+	}
 
 	afe->suspended = false;
 	return 0;
-- 
2.18.0