linux-kernel - Re: [PATCH] soundwire: stream: fix an invalid free

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Message-ID: <20200907141402.GC2639@vkoul-mobl>
Date:   Mon, 7 Sep 2020 19:44:02 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     trix@...hat.com
Cc:     yung-chuan.liao@...ux.intel.com,
        pierre-louis.bossart@...ux.intel.com, sanyog.r.kale@...el.com,
        natechancellor@...il.com, ndesaulniers@...gle.com,
        guennadi.liakhovetski@...ux.intel.com,
        kai.vehmanen@...ux.intel.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com
Subject: Re: [PATCH] soundwire: stream: fix an invalid free

Hello Tom,

On 05-09-20, 12:26, trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
> 
> clang static analyzer reports this problem
> 
> stream.c:872:2: warning: Argument to kfree() is a constant
>   address (18446744073709551092), which is not memory
>   allocated by malloc()
>         kfree(stream);
>         ^~~~~~~~~~~~~
> 
> In sdw_shutdown_stream() the stream to free is set by
> a call to snd_soc_dai_get_sdw_stream().  The problem block
> is the check if the call was successful.
> 
> 	if (!sdw_stream) {
> 		dev_err(rtd->dev, "no stream found...
> 		return;
> 	}
> 
> When snd_soc_dai_get_sdw_stream() fails, it does not
> always return null, sometimes it returns -ENOTSUPP.
> 
> So also check for error codes.
> Fixes: 4550569bd779 ("soundwire: stream: add helper to startup/shutdown streams")
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/soundwire/stream.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
> index 6e36deb505b1..950231d593c2 100644
> --- a/drivers/soundwire/stream.c
> +++ b/drivers/soundwire/stream.c
> @@ -1913,7 +1913,7 @@ void sdw_shutdown_stream(void *sdw_substream)
>  
>  	sdw_stream = snd_soc_dai_get_sdw_stream(dai, substream->stream);
>  
> -	if (!sdw_stream) {
> +	if (IS_ERR_OR_NULL(sdw_stream)) {

Thanks for the patch. Please see commit 3471d2a192ba ("soundwire:
stream: fix NULL/IS_ERR confusion") in soundwire-next. This has already
been updated to IS_ERR() and Bard has already sent patches for
snd_soc_dai_get_sdw_stream() to return proper values.

So I you can rerun this on next, you should see this fixed.

-- 
~Vinod