linux-kernel - Re: [PATCH v3] ASoC: wcd934x: fix error handling in wcd934x_codec_parse

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Message-ID: <unqzejlsp6emzja5ry32smzlinntodgbioyojr5osiqddh2ppi@mtf4e7y4cids>
Date: Tue, 23 Sep 2025 06:26:15 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
To: Ma Ke <make24@...as.ac.cn>
Cc: srini@...nel.org, lgirdwood@...il.com, broonie@...nel.org, perex@...ex.cz,
        tiwai@...e.com, pierre-louis.bossart@...ux.dev,
        linux-sound@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v3] ASoC: wcd934x: fix error handling in
 wcd934x_codec_parse_data()

On Tue, Sep 23, 2025 at 10:38:28AM +0800, Ma Ke wrote:
> wcd934x_codec_parse_data() contains a device reference count leak in
> of_slim_get_device() where device_find_child() increases the reference
> count of the device but this reference is not properly decreased in
> the success path. Add put_device() in wcd934x_codec_parse_data() and
> add devm_add_action_or_reset() in the probe function, which ensures
> that the reference count of the device is correctly managed.
> 
> Memory leak in regmap_init_slimbus() as the allocated regmap is not
> released when the device is removed. Using devm_regmap_init_slimbus()
> instead of regmap_init_slimbus() to ensure automatic regmap cleanup on
> device removal.
> 
> Calling path: of_slim_get_device() -> of_find_slim_device() ->
> device_find_child(). As comment of device_find_child() says, 'NOTE:
> you will need to drop the reference with put_device() after use.'.
> 
> Found by code review.
> 
> Cc: stable@...r.kernel.org
> Fixes: a61f3b4f476e ("ASoC: wcd934x: add support to wcd9340/wcd9341 codec")
> Signed-off-by: Ma Ke <make24@...as.ac.cn>
> ---
> Changes in v3:
> - added a wrapper function due to the warning report from kernel test robot;
> Changes in v2:
> - modified the handling in the success path and fixed the memory leak for regmap as suggestions.
> ---
>  sound/soc/codecs/wcd934x.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/sound/soc/codecs/wcd934x.c b/sound/soc/codecs/wcd934x.c
> index 1bb7e1dc7e6b..d9d8cf64977a 100644
> --- a/sound/soc/codecs/wcd934x.c
> +++ b/sound/soc/codecs/wcd934x.c
> @@ -5831,6 +5831,15 @@ static const struct snd_soc_component_driver wcd934x_component_drv = {
>  	.endianness = 1,
>  };
>  
> +static void wcd934x_put_device_action(void *data)
> +{
> +	struct device *dev = data;
> +
> +	if (dev) {

Can it be NULL here? Can put_device() cope with NULL being passed to it?

> +		put_device(dev);
> +	}
> +}
> +
>  static int wcd934x_codec_parse_data(struct wcd934x_codec *wcd)
>  {
>  	struct device *dev = &wcd->sdev->dev;
> @@ -5847,11 +5856,13 @@ static int wcd934x_codec_parse_data(struct wcd934x_codec *wcd)
>  		return dev_err_probe(dev, -EINVAL, "Unable to get SLIM Interface device\n");
>  
>  	slim_get_logical_addr(wcd->sidev);
> -	wcd->if_regmap = regmap_init_slimbus(wcd->sidev,
> +	wcd->if_regmap = devm_regmap_init_slimbus(wcd->sidev,
>  				  &wcd934x_ifc_regmap_config);
> -	if (IS_ERR(wcd->if_regmap))
> +	if (IS_ERR(wcd->if_regmap)) {
> +		put_device(&wcd->sidev->dev);
>  		return dev_err_probe(dev, PTR_ERR(wcd->if_regmap),
>  				     "Failed to allocate ifc register map\n");
> +	}
>  
>  	of_property_read_u32(dev->parent->of_node, "qcom,dmic-sample-rate",
>  			     &wcd->dmic_sample_rate);
> @@ -5893,6 +5904,10 @@ static int wcd934x_codec_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	ret = devm_add_action_or_reset(dev, wcd934x_put_device_action, &wcd->sidev->dev);
> +	if (ret)
> +		return ret;
> +
>  	/* set default rate 9P6MHz */
>  	regmap_update_bits(wcd->regmap, WCD934X_CODEC_RPM_CLK_MCLK_CFG,
>  			   WCD934X_CODEC_RPM_CLK_MCLK_CFG_MCLK_MASK,
> -- 
> 2.17.1
> 

-- 
With best wishes
Dmitry