linux-kernel - [PATCH v2] isoc: mediatek: Fix dereference of null pointer while alloc fail

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Message-Id: <20211217165220.675485-1-jiasheng@iscas.ac.cn>
Date:   Sat, 18 Dec 2021 00:52:20 +0800
From:   Jiasheng Jiang <jiasheng@...as.ac.cn>
To:     matthias.bgg@...il.com, lgirdwood@...il.com, broonie@...nel.org
Cc:     linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Jiasheng Jiang <jiasheng@...as.ac.cn>
Subject: [PATCH v2] isoc: mediatek: Fix dereference of null pointer while alloc fail

Sorry, maybe I do not fully understand the meaning of your review
comments and I really fail to behave polite.
This time I carefully check all the comments and believe I have already
obey all the request.
The message as follow is my new comments.
If there are also problems, please let me know and I will correct in
time.

Because devm_clk_get() will not always success.
It should be better to check the return value in order to
avoid use of error pointer in case of the failure.
Therefore, we should use the IS_ERR() to check the error pointer and
return -ENOMEM if it is and 0 if not.
Also, we deal with the return value in init_scp.

Fixes: 6078c651947a ("soc: mediatek: Refine scpsys to support multiple platform")
Signed-off-by: Jiasheng Jiang <jiasheng@...as.ac.cn>
---
Changelog:

v1 -> v2

*Change 1. Correct the commit message.
---
 drivers/soc/mediatek/mtk-scpsys.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
index ca75b14931ec..778d6ffc42b8 100644
--- a/drivers/soc/mediatek/mtk-scpsys.c
+++ b/drivers/soc/mediatek/mtk-scpsys.c
@@ -411,12 +411,16 @@ static int scpsys_power_off(struct generic_pm_domain *genpd)
 	return ret;
 }
 
-static void init_clks(struct platform_device *pdev, struct clk **clk)
+static int init_clks(struct platform_device *pdev, struct clk **clk)
 {
 	int i;
 
-	for (i = CLK_NONE + 1; i < CLK_MAX; i++)
+	for (i = CLK_NONE + 1; i < CLK_MAX; i++) {
 		clk[i] = devm_clk_get(&pdev->dev, clk_names[i]);
+		if (IS_ERR(clk[i]))
+			return -ENOMEM;
+	}
+	return 0;
 }
 
 static struct scp *init_scp(struct platform_device *pdev,
@@ -426,7 +430,7 @@ static struct scp *init_scp(struct platform_device *pdev,
 {
 	struct genpd_onecell_data *pd_data;
 	struct resource *res;
-	int i, j;
+	int i, j, ret;
 	struct scp *scp;
 	struct clk *clk[CLK_MAX];
 
@@ -481,7 +485,9 @@ static struct scp *init_scp(struct platform_device *pdev,
 
 	pd_data->num_domains = num;
 
-	init_clks(pdev, clk);
+	ret = init_clks(pdev, clk);
+	if (ret)
+		return ERR_PTR(-ENOMEM);
 
 	for (i = 0; i < num; i++) {
 		struct scp_domain *scpd = &scp->domains[i];
-- 
2.25.1