linux-kernel - Re: [PATCH v2] ASoC: fsl_easrc: Check for null pointer before dereferencing "ctx" in fsl_easrc_hw

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Date:   Sun, 26 Apr 2020 15:20:51 -0700
From:   Nicolin Chen <nicoleotsuka@...il.com>
To:     Shengjiu Wang <shengjiu.wang@....com>
Cc:     timur@...nel.org, Xiubo.Lee@...il.com, festevam@...il.com,
        broonie@...nel.org, alsa-devel@...a-project.org,
        lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.com,
        linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] ASoC: fsl_easrc: Check for null pointer before
 dereferencing "ctx" in fsl_easrc_hw_free()

On Sat, Apr 25, 2020 at 03:19:29PM +0800, Shengjiu Wang wrote:
> The patch 955ac624058f: "ASoC: fsl_easrc: Add EASRC ASoC CPU DAI
> drivers" from Apr 16, 2020, leads to the following Smatch complaint:
> 
> sound/soc/fsl/fsl_easrc.c:1529 fsl_easrc_hw_free()
> warn: variable dereferenced before check 'ctx' (see line 1527)
> 
> sound/soc/fsl/fsl_easrc.c
>   1526          struct fsl_asrc_pair *ctx = runtime->private_data;
>   1527          struct fsl_easrc_ctx_priv *ctx_priv = ctx->private;
>                                                       ^^^^^
> Dereference
> 
>   1528
>   1529          if (ctx && (ctx_priv->ctx_streams & BIT(substream->stream))) {
>                     ^^^
> This check is too late, to prevent a NULL dereference.
> 
>   1530                  ctx_priv->ctx_streams &= ~BIT(substream->stream);
>   1531                  fsl_easrc_release_context(ctx);
> 
> Fixes: 955ac624058f ("ASoC: fsl_easrc: Add EASRC ASoC CPU DAI drivers")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Shengjiu Wang <shengjiu.wang@....com>

Acked-by: Nicolin Chen <nicoleotsuka@...il.com>