Re: [bug report] ALSA: usb-audio: Add error checks against get_min_max*()

[Takashi Iwai <tiwai@suse.de>]

On Tue, 14 Apr 2026 10:27:32 +0200,
Dan Carpenter wrote:
> 
> Hello Rong Zhang,
> 
> Commit 4f55a85cd4fc ("ALSA: usb-audio: Add error checks against
> get_min_max*()") from Apr 11, 2026 (linux-next), leads to the
> following Smatch static checker warning:
> 
> 	sound/usb/mixer.c:2711 build_audio_procunit()
> 	error: uninitialized symbol 'err'.
> 
> sound/usb/mixer.c
>     2660                 if (state->mixer->protocol > UAC_VERSION_1 &&
>     2661                     !uac_v2v3_control_is_writeable(controls[valinfo->control / 8],
>     2662                                                    valinfo->control))
>     2663                         cval->master_readonly = 1;
>     2664 
>     2665                 /* get min/max values */
>     2666                 switch (type) {
>     2667                 case UAC_PROCESS_UP_DOWNMIX: {
>     2668                         bool mode_sel = false;
>     2669 
>     2670                         switch (state->mixer->protocol) {
>     2671                         case UAC_VERSION_1:
>     2672                         case UAC_VERSION_2:
>     2673                         default:
>     2674                                 if (cval->control == UAC_UD_MODE_SELECT)
>     2675                                         mode_sel = true;
>     2676                                 break;
>     2677                         case UAC_VERSION_3:
>     2678                                 if (cval->control == UAC3_UD_MODE_SELECT)
>     2679                                         mode_sel = true;
>     2680                                 break;
>     2681                         }
>     2682 
>     2683                         if (mode_sel) {
>     2684                                 __u8 *control_spec = uac_processing_unit_specific(desc,
>     2685                                                                 state->mixer->protocol);
>     2686                                 cval->min = 1;
>     2687                                 cval->max = control_spec[0];
>     2688                                 cval->res = 1;
>     2689                                 cval->initialized = 1;
>     2690                                 break;
> 
> err not initialized at this break.

Thanks for the report.  Let's plug the hole with a simple fix to add
"err = 0" here.

I'm going to submit a fix patch.


Takashi