Re: [RFC PATCH] ASoC: Intel: avs: Fix reading 1 or more bytes from a region of size 0

[Brahmajit Das <listout@xxxxxxxxxxx>]

On 02.09.2025 10:15, Takashi Iwai wrote:
> On Tue, 02 Sep 2025 10:08:12 +0200,
> Brahmajit Das wrote:
> > 
> > Building the next tree with GCC 16, results in the following error:
> > 
> > sound/soc/intel/avs/path.c:137:38: error: ‘strcmp’ reading 1 or more bytes from a region of size 0 [-Werror=stringop-overread]
> >   137 |         return id->id == id2->id && !strcmp(id->tplg_name, id2->tplg_name);
> >       |                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
...snip...
> > Signed-off-by: Brahmajit Das <listout@xxxxxxxxxxx>
> > ---
> >  sound/soc/intel/avs/path.c | 3 ++-
> >  1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/sound/soc/intel/avs/path.c b/sound/soc/intel/avs/path.c
> > index 7aa20fcf1a33..8c3df2002b58 100644
> > --- a/sound/soc/intel/avs/path.c
> > +++ b/sound/soc/intel/avs/path.c
> > @@ -134,7 +134,8 @@ static struct avs_tplg_path *avs_condpath_find_variant(struct avs_dev *adev,
> >  static bool avs_tplg_path_template_id_equal(struct avs_tplg_path_template_id *id,
> >  					    struct avs_tplg_path_template_id *id2)
> >  {
> > -	return id->id == id2->id && !strcmp(id->tplg_name, id2->tplg_name);
> > +	return id->id == id2->id &&
> > +	       !strncmp(id->tplg_name, id2->tplg_name, strlen(id->tplg_name));
> 
> Please use sizeof()-1 instead of strlen(), as it's a fixed size array.
> 
> Practically seen, it's likely a false-positive from the new compiler.
> But it's still safer to add the boundary check in the code itself.
> 
> 
> thanks,
> 
> Takashi
So, I was testing again and with sizeof, I'm getting

sound/soc/intel/avs/path.c:137:38: error: ‘strncmp’ specified bound 43 exceeds source size 0 [-Werror=stringop-overread]
  137 |         return id->id == id2->id && !strncmp(id->tplg_name, id2->tplg_name,
      |                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  138 |                                              sizeof(id->tplg_name) - 1);
      |                                              ~~~~~~~~~~~~~~~~~~~~~~~~~~

So my previous v2 is wrong, please ignore that.
Whereas, with strlen there's no warning :( . I'm quite confused, and
lack the GCC knowledge.

-- 
Regards,
listout