Re: [PATCH] greybus: audio: ensure module is set to avoid crash on dev_err message

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Sep 23, 2016 at 11:25:40AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.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@canonical.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?