linux-kernel - Re: [PATCH] ASoC: mt8365: Fix using uninitialized value "i2s

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Message-ID: <ZuGG3jk6oqq7sUMw@iZbp1asjb3cy8ks0srf007Z>
Date: Wed, 11 Sep 2024 20:02:38 +0800
From: Qianqiang Liu <qianqiang.liu@....com>
To: Mark Brown <broonie@...nel.org>
Cc: amergnat@...libre.com, angelogioacchino.delregno@...labora.com,
	lgirdwood@...il.com, matthias.bgg@...il.com,
	linux-sound@...r.kernel.org, linux-mediatek@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: mt8365: Fix using uninitialized value "i2s_data"
 issue

On Wed, Sep 11, 2024 at 12:41:15PM +0100, Mark Brown wrote:
> On Wed, Sep 11, 2024 at 07:36:33PM +0800, Qianqiang Liu wrote:
> > On Wed, Sep 11, 2024 at 11:52:58AM +0100, Mark Brown wrote:
> > > On Wed, Sep 11, 2024 at 08:15:17AM +0800, Qianqiang Liu wrote:
> 
> > > >  	spin_lock_irqsave(&afe_priv->afe_ctrl_lock, flags);
> 
> > > > +	if (!i2s_data) {
> > > > +		spin_unlock_irqrestore(&afe_priv->afe_ctrl_lock, flags);
> > > > +		return;
> > > > +	}
> 
> > > Why would we look up i2s_data without the lock, take the lock, then
> > > check if we actually found it?  That doesn't seem right.
> 
> > Just check the "i2s_data" is NULL or not.
> 
> That doesn't address my question at all.

How about this new patch:

diff --git a/sound/soc/mediatek/mt8365/mt8365-dai-i2s.c b/sound/soc/mediatek/mt8365/mt8365-dai-i2s.c
index 3482d8f8b4e7..11b9a5bc7163 100644
--- a/sound/soc/mediatek/mt8365/mt8365-dai-i2s.c
+++ b/sound/soc/mediatek/mt8365/mt8365-dai-i2s.c
@@ -465,13 +465,16 @@ void mt8365_afe_set_i2s_out_enable(struct mtk_base_afe *afe, bool enable)
 	int i;
 	unsigned long flags;
 	struct mt8365_afe_private *afe_priv = afe->platform_priv;
-	struct mtk_afe_i2s_priv *i2s_data;
+	struct mtk_afe_i2s_priv *i2s_data = NULL;
 
 	for (i = 0; i < DAI_I2S_NUM; i++) {
 		if (mt8365_i2s_priv[i].adda_link)
 			i2s_data = afe_priv->dai_priv[mt8365_i2s_priv[i].id];
 	}
 
+	if (!i2s_data)
+		return;
+
 	spin_lock_irqsave(&afe_priv->afe_ctrl_lock, flags);
 
 	if (enable) {

-- 
Best,
Qianqiang Liu