Re: [patch] ALSA: mixart: don't print an unintialized variable on error

[Takashi Sakamoto <o-takashi@sakamocchi.jp>]

On Jul 13 2016 19:18, Takashi Sakamoto wrote:
> Hi,
> 
> On Jul 13 2016 18:59, Dan Carpenter wrote:
>> My static checker complains that "resp" could be unitialized on error
>> when we print its value.
>>
>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>>
>> diff --git a/sound/pci/mixart/mixart_mixer.c
>> b/sound/pci/mixart/mixart_mixer.c
>> index 58fd79eb..51e5349 100644
>> --- a/sound/pci/mixart/mixart_mixer.c
>> +++ b/sound/pci/mixart/mixart_mixer.c
>> @@ -965,7 +965,7 @@ static int mixart_update_monitoring(struct
>> snd_mixart* chip, int channel)
>>       int err;
>>       struct mixart_msg request;
>>       struct mixart_set_out_audio_level audio_level;
>> -    u32 resp;
>> +    u32 resp = 0;
>>
>>       if(chip->pipe_out_ana.status = PIPE_UNDEFINED)
>>           return -EINVAL; /* no pipe defined */
> 
> The 'resp' variable is firstly given to snd_mixart_send_msg().
> 
> static int mixart_update_monitoring(struct snd_mixart* chip,
>                                     int channel)
> {
>     ...
>     err = snd_mixart_send_msg(chip->mgr, &request, sizeof(resp), &resp);
>     if((err<0) || resp) {
>         dev_dbg(chip->card->dev,
>                 "error MSG_CONNECTOR_SET_OUT_AUDIO_LEVEL card(%d)
> resp(%x)\n",
>                 chip->chip_idx, resp);
>         return -EINVAL;
>     }
>     return 0;
> }
> 
> When the function, snd_mixart_send_msg(), assigns nothing to the
> variable in error cases, dev_dbg() prints uninitialized value.

Hm. I realized that this interpretation is not enough. When value of the
error is not negative, snd_mixart_send_msg() can assign something to the
resp variable, then dev_dbg() is called. In short, when the function is
successful, there's a case that the message is processed. This is a bit
strange...

I think a condition statement for the resp variable is needless here, as
long as the variable is initialized ahead...

> Reviewed-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>

Anyway, it's better to initialize it.


Regards

Takashi Sakamoto