linux-kernel - Re: [PATCH] greybus: audio: ensure module is set to avoid crash on dev

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Message-ID: <20160923165802.GA7575@kroah.com>
Date:   Fri, 23 Sep 2016 18:58:02 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Colin King <colin.king@...onical.com>
Cc:     Vaibhav Agarwal <vaibhav.sr@...il.com>,
        Johan Hovold <johan@...nel.org>, Alex Elder <elder@...nel.org>,
        devel@...verdev.osuosl.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] greybus: audio: ensure module is set to avoid crash on
 dev_err message

On Fri, Sep 23, 2016 at 11:25:40AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@...onical.com>
> 
> Currently, if info is null, the dev_err message is dereferencing an
> uninitialized module pointer.  Instead, initialize module before the
> dev_err call to fix this issue.
> 
> Found using static analysis with cppcheck:
> [drivers/staging/greybus/audio_topology.c:175]: (error)
>   Uninitialized variable: module
> 
> Signed-off-by: Colin Ian King <colin.king@...onical.com>
> ---
>  drivers/staging/greybus/audio_topology.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/staging/greybus/audio_topology.c b/drivers/staging/greybus/audio_topology.c
> index 5eef536..c43a959 100644
> --- a/drivers/staging/greybus/audio_topology.c
> +++ b/drivers/staging/greybus/audio_topology.c
> @@ -171,6 +171,9 @@ static int gbcodec_mixer_ctl_info(struct snd_kcontrol *kcontrol,
>  	data = (struct gbaudio_ctl_pvt *)kcontrol->private_value;
>  	info = (struct gb_audio_ctl_elem_info *)data->info;
>  
> +	module = find_gb_module(gbcodec, kcontrol->id.name);
> +	if (!module)
> +		return -EINVAL;

How do you know you can get a module at this point in time, you haven't
looked at the type of info to know that?

I agree that there is an issue here, but I don't think this is the
correct fix.  Vaibhav?