Re: [PATCH] ASoC: dapm: fix bounds checker error in dapm_widget_list_create

[Kees Cook <kees@kernel.org>]

On Mon, Oct 28, 2024 at 04:58:58PM -0600, Gustavo A. R. Silva wrote:
> 
> 
> On 28/10/24 16:50, Aleksei Vetrov wrote:
> > The widgets array in the snd_soc_dapm_widget_list has a __counted_by
> > attribute attached to it, which points to the num_widgets variable. This
> > attribute is used in bounds checking, and if it is not set before the
> > array is filled, then the bounds sanitizer will issue a warning or a
> > kernel panic if CONFIG_UBSAN_TRAP is set.
> > 
> > This patch sets the size of the widgets list calculated with
> > list_for_each as the initial value for num_widgets as it is used for
> > allocating memory for the array. It is updated with the actual number of
> > added elements after the array is filled.
> 
> As in the previous patch, this should include the following tag
> (and probably CC stable):
> 
> Fixes: 80e698e2df5b ("ASoC: soc-dapm: Annotate struct snd_soc_dapm_widget_list with __counted_by")

Whoops! My mistake. :) Thanks for catching this one!

Reviewed-by: Kees Cook <kees@kernel.org>

-Kees

> 
> Thanks
> -- 
> Gustavo
> 
> > 
> > Signed-off-by: Aleksei Vetrov <vvvvvv@google.com>
> > ---
> >   sound/soc/soc-dapm.c | 2 ++
> >   1 file changed, 2 insertions(+)
> > 
> > diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c
> > index c34934c31ffec3970b34b24dcaa0826dfb7d8e86..99521c784a9b16a232a558029a2f3e88bd8ebfb1 100644
> > --- a/sound/soc/soc-dapm.c
> > +++ b/sound/soc/soc-dapm.c
> > @@ -1147,6 +1147,8 @@ static int dapm_widget_list_create(struct snd_soc_dapm_widget_list **list,
> >   	if (*list == NULL)
> >   		return -ENOMEM;
> > +	(*list)->num_widgets = size;
> > +
> >   	list_for_each_entry(w, widgets, work_list)
> >   		(*list)->widgets[i++] = w;
> > 
> > ---
> > base-commit: 81983758430957d9a5cb3333fe324fd70cf63e7e
> > change-id: 20241028-soc-dapm-bounds-checker-fix-5bae621455b2
> > 
> > Best regards,
> 
> 

-- 
Kees Cook