Re: [bug report] ASoC: Intel: cht_bsw_rt5645: Set card.components string

[Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>]

Thanks Dan for the report.


> Commit f87b4402163b ("ASoC: Intel: cht_bsw_rt5645: Set
> card.components string") from Nov 26, 2023 (linux-next), leads to the
> following Smatch static checker warning:
> 
> 	sound/soc/intel/boards/cht_bsw_rt5645.c:587 snd_cht_mc_probe()
> 	error: we previously assumed 'adev' could be null (see line 581)
> 
> sound/soc/intel/boards/cht_bsw_rt5645.c
>     570         /* set correct codec name */
>     571         for (i = 0; i < ARRAY_SIZE(cht_dailink); i++)
>     572                 if (cht_dailink[i].codecs->name &&
>     573                     !strcmp(cht_dailink[i].codecs->name,
>     574                             "i2c-10EC5645:00")) {
>     575                         dai_index = i;
>     576                         break;
>     577                 }
>     578 
>     579         /* fixup codec name based on HID */
>     580         adev = acpi_dev_get_first_match_dev(mach->id, NULL, -1);
>     581         if (adev) {
>                     ^^^^
> The old code assumes adev can be NULL
> 
>     582                 snprintf(cht_rt5645_codec_name, sizeof(cht_rt5645_codec_name),
>     583                          "i2c-%s", acpi_dev_name(adev));
>     584                 cht_dailink[dai_index].codecs->name = cht_rt5645_codec_name;
>     585         }
>     586         /* acpi_get_first_physical_node() returns a borrowed ref, no need to deref */
> --> 587         codec_dev = acpi_get_first_physical_node(adev);
>                                                          ^^^^
> Unchecked dereference

This looks like a problem in multiple machine drivers sharing similar
code, if we want to consistently check the output we probably need
something like https://github.com/thesofproject/linux/pull/5117 ?