Re: [PATCH] ALSA: usb-audio: Initialize status1 to fix uninitialized symbol errors

[Takashi Iwai <tiwai@suse.de>]

On Wed, 03 Dec 2025 13:01:48 +0100,
HariKrishna Sagala wrote:
> 
> On Wed, 3 Dec 2025, Takashi Iwai wrote:
> 
> > On Wed, 03 Dec 2025 12:22:27 +0100,
> > HariKrishna Sagala wrote:
> > >
> > > On Wed, 3 Dec 2025, Takashi Iwai wrote:
> > >
> > > > On Wed, 03 Dec 2025 12:01:35 +0100,
> > > > HariKrishna Sagala wrote:
> > > > >
> > > > > On Wed, 3 Dec 2025, Takashi Iwai wrote:
> > > > >
> > > > > > On Wed, 03 Dec 2025 09:33:20 +0100,
> > > > > > hariconscious@gmail.com wrote:
> > > > > > >
> > > > > > > From: HariKrishna Sagala <hariconscious@gmail.com>
> > > > > > >
> > > > > > > Initialize 'status1' with a default value to resolve the static analysis
> > > > > > > smatch reported error "uninitialized symbol 'status1'".
> > > > > > > The 'status1' variable is used to create a buff using "kmemdup".
> > > > > > > So, ensure to initialize the value before it is read.
> > > > > > >
> > > > > > > Signed-off-by: HariKrishna Sagala <hariconscious@gmail.com>
> > > > > > > ---
> > > > > > > This patch fixes the below smatch reported errors.
> > > > > > > sound/usb/mixer_quirks.c:2462 snd_rme_rate_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2467 snd_rme_rate_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2472 snd_rme_rate_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2495 snd_rme_sync_state_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2501 snd_rme_sync_state_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2522 snd_rme_spdif_if_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2535 snd_rme_spdif_format_get() error: uninitialized symbol 'status1'.
> > > > > > > sound/usb/mixer_quirks.c:2548 snd_rme_sync_source_get() error: uninitialized symbol 'status1'.
> > > > > > >
> > > > > > > The below is the flow of 'status1' it is used before initialization.
> > > > > > >
> > > > > > > snd_rme_rate_get -> status1 is uninitialized and passed
> > > > > > > 	snd_rme_get_status1 -> passed as is
> > > > > > > 		snd_rme_read_value -> passed as is
> > > > > > > 			snd_usb_ctl_msg -> created buf from status1 using kmemdup
> > > > > > > 				usb_control_msg -> sent buf for reading/writing
> > > > > > >
> > > > > > > Description of "usb_control_msg", states as
> > > > > > > " * @data: pointer to the data to send"
> > > > > > >
> > > > > > > Later from Usb control request, dst buf is copied to src buf but usb
> > > > > > > control msg request is made before initialization.
> > > > > > >
> > > > > > > Thank you.
> > > > > > >
> > > > > > >  sound/usb/mixer_quirks.c | 10 +++++-----
> > > > > > >  1 file changed, 5 insertions(+), 5 deletions(-)
> > > > > > >
> > > > > > > diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
> > > > > > > index 828af3095b86..06903c5de087 100644
> > > > > > > --- a/sound/usb/mixer_quirks.c
> > > > > > > +++ b/sound/usb/mixer_quirks.c
> > > > > > > @@ -2449,7 +2449,7 @@ static int snd_rme_get_status1(struct snd_kcontrol *kcontrol,
> > > > > > >  static int snd_rme_rate_get(struct snd_kcontrol *kcontrol,
> > > > > > >  			    struct snd_ctl_elem_value *ucontrol)
> > > > > > >  {
> > > > > > > -	u32 status1;
> > > > > > > +	u32 status1 = 0;
> > > > > > >  	u32 rate = 0;
> > > > > > >  	int idx;
> > > > > > >  	int err;
> > > > > > > @@ -2483,7 +2483,7 @@ static int snd_rme_rate_get(struct snd_kcontrol *kcontrol,
> > > > > > >  static int snd_rme_sync_state_get(struct snd_kcontrol *kcontrol,
> > > > > > >  				  struct snd_ctl_elem_value *ucontrol)
> > > > > > >  {
> > > > > > > -	u32 status1;
> > > > > > > +	u32 status1 = 0;
> > > > > > >  	int idx = SND_RME_CLOCK_NOLOCK;
> > > > > > >  	int err;
> > > > > > >
> > > > > > > @@ -2513,7 +2513,7 @@ static int snd_rme_sync_state_get(struct snd_kcontrol *kcontrol,
> > > > > > >  static int snd_rme_spdif_if_get(struct snd_kcontrol *kcontrol,
> > > > > > >  				struct snd_ctl_elem_value *ucontrol)
> > > > > > >  {
> > > > > > > -	u32 status1;
> > > > > > > +	u32 status1 = 0;
> > > > > > >  	int err;
> > > > > > >
> > > > > > >  	err = snd_rme_get_status1(kcontrol, &status1);
> > > > > > > @@ -2526,7 +2526,7 @@ static int snd_rme_spdif_if_get(struct snd_kcontrol *kcontrol,
> > > > > > >  static int snd_rme_spdif_format_get(struct snd_kcontrol *kcontrol,
> > > > > > >  				    struct snd_ctl_elem_value *ucontrol)
> > > > > > >  {
> > > > > > > -	u32 status1;
> > > > > > > +	u32 status1 = 0;
> > > > > > >  	int err;
> > > > > > >
> > > > > > >  	err = snd_rme_get_status1(kcontrol, &status1);
> > > > > > > @@ -2539,7 +2539,7 @@ static int snd_rme_spdif_format_get(struct snd_kcontrol *kcontrol,
> > > > > > >  static int snd_rme_sync_source_get(struct snd_kcontrol *kcontrol,
> > > > > > >  				   struct snd_ctl_elem_value *ucontrol)
> > > > > > >  {
> > > > > > > -	u32 status1;
> > > > > > > +	u32 status1 = 0;
> > > > > > >  	int err;
> > > > > > >
> > > > > > >  	err = snd_rme_get_status1(kcontrol, &status1);
> > > > > > >
> > > > > >
> > > > > > The warning itself is rather dubious.  But it'd certainly give a safer
> > > > > > feeling to cover the uninitialized variables, so it would still make
> > > > > > some sense.
> > > > > >
> > > > > > But, the code change can be improved.  e.g. initialize the value in
> > > > > > the callee side, instead of callers; then it'll reduce all changes to
> > > > > > a one-liner.
> > > > > >
> > > > > > At the next time, please look at the patterns you changed more closely
> > > > > > and think again whether it's the best change or not before submission.
> > > > > > On the second look, often you see things from a different perspective
> > > > > > :)
> > > > > >
> > > > > >
> > > > > > thanks,
> > > > > >
> > > > > > Takashi
> > > > > >
> > > > >
> > > > > Hi Takashi,
> > > > >
> > > > > Thank you for the feedback and complement.
> > > > > Yes, will check the pattern and avoid this going forward.
> > > > > As all the functions call "snd_rme_get_status1",
> > > > > initialized here but smatch didn't silence them.
> > > > >
> > > > > I prefer initializing a variable in caller side as it owns
> > > > > and aware of initialized value sent.
> > > > >
> > > > > Sorry, if I had misunderstood your suggestion.
> > > >
> > > > Well, you seem driven too much by smatch.  Just look at your patch
> > > > again.
> > > >
> > > > You're repeating the same initializations and passing to the same
> > > > function.  And those are the only callers of snd_rme_get_status1().
> > > > So, instead of initializing in the caller side, initialize the value
> > > > in snd_rme_get_status1().  Then the whole your changes will be
> > > > oneliner like below.
> > > >
> > > >
> > > > Takashi
> > > >
> > > > --- a/sound/usb/mixer_quirks.c
> > > > +++ b/sound/usb/mixer_quirks.c
> > > > @@ -2548,6 +2548,7 @@ static int snd_rme_get_status1(struct snd_kcontrol *kcontrol,
> > > >  	CLASS(snd_usb_lock, pm)(chip);
> > > >  	if (pm.err < 0)
> > > >  		return pm.err;
> > > > +	*status1 = 0;
> > > >  	return snd_rme_read_value(chip, SND_RME_GET_STATUS1, status1);
> > > >  }
> > > >
> > > >
> > >
> > > Hi Takashi,
> > >
> > > Yes, tried that before, smatch didn't silence them.
> >
> > Then it's an obvious failure of smatch.
> >
> > Or you might set *status1 = 0 at the beginning of
> > snd_rme_get_status1() although it makes little sense.
> >
> > > If it is worth having this change though they are not silenced,
> > > will raise v2 otherwise will drop this patch.
> >
> > If the smatch still complains, it's not worth.
> >
> >
> > Takashi
> >
> 
> Hi Takashi,
> 
> This is the change I tried but smatch didn't silence them.
> 
> diff --git a/sound/usb/mixer_quirks.c b/sound/usb/mixer_quirks.c
> index 828af3095b86..10354576d325 100644
> --- a/sound/usb/mixer_quirks.c
> +++ b/sound/usb/mixer_quirks.c
> @@ -2443,6 +2443,7 @@ static int snd_rme_get_status1(struct snd_kcontrol
> *kcontrol,
>         CLASS(snd_usb_lock, pm)(chip);
>         if (pm.err < 0)
>                 return pm.err;
> +       *status1 = 0;
>         return snd_rme_read_value(chip, SND_RME_GET_STATUS1, status1);
>  }
> 
> Below are reported with the change, as seen they are not silenced.
> 
> sound/usb/mixer_quirks.c:2463 snd_rme_rate_get() error: uninitialized
> symbol 'status1'.
> sound/usb/mixer_quirks.c:2468 snd_rme_rate_get() error: uninitialized
> symbol 'status1'.
> sound/usb/mixer_quirks.c:2473 snd_rme_rate_get() error: uninitialized
> symbol 'status1'.
> sound/usb/mixer_quirks.c:2496 snd_rme_sync_state_get() error:
> uninitialized symbol 'status1'.
> sound/usb/mixer_quirks.c:2502 snd_rme_sync_state_get() error:
> uninitialized symbol 'status1'.
> sound/usb/mixer_quirks.c:2523 snd_rme_spdif_if_get() error: uninitialized
> symbol 'status1'.
> sound/usb/mixer_quirks.c:2536 snd_rme_spdif_format_get() error:
> uninitialized symbol 'status1'.
> sound/usb/mixer_quirks.c:2549 snd_rme_sync_source_get() error:
> uninitialized symbol 'status1'.
> sound/usb/mixer_quirks.c:4137 snd_djm_controls_info() warn: potential
> spectre issue 'ctl->options' [r] (local cap)

As mentioned, try to put *status1=0 line before CLASS() call in the
above.  If this still doesn't help, it's a bug of smatch, and we
should ignore it.


Takashi