On 10/4/23 01:28, Kees Cook wrote:

Prepare for the coming implementation by GCC and Clang of the __counted_by attribute. Flexible array members annotated with __counted_by can have their accesses bounds-checked at run-time via CONFIG_UBSAN_BOUNDS (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).

As found with Coccinelle[1], add __counted_by for struct snd_soc_dapm_widget_list. Additionally, since the element count member must be set before accessing the annotated flexible array member, move its initialization earlier.

Cc: Liam Girdwood lgirdwood@gmail.com Cc: Mark Brown broonie@kernel.org Cc: Jaroslav Kysela perex@perex.cz Cc: Takashi Iwai tiwai@suse.com Cc: "Gustavo A. R. Silva" gustavoars@kernel.org Cc: alsa-devel@alsa-project.org Cc: linux-hardening@vger.kernel.org Link: https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_... [1] Signed-off-by: Kees Cook keescook@chromium.org

Reviewed-by: Gustavo A. R. Silva gustavoars@kernel.org

Thanks -- Gustavo

---

include/sound/soc-dapm.h | 2 +- sound/soc/soc-dapm.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/sound/soc-dapm.h b/include/sound/soc-dapm.h index d2faec9a323e..51516c93916e 100644 --- a/include/sound/soc-dapm.h +++ b/include/sound/soc-dapm.h @@ -717,7 +717,7 @@ struct snd_soc_dapm_context { /* A list of widgets associated with an object, typically a snd_kcontrol */ struct snd_soc_dapm_widget_list { int num_widgets;

• struct snd_soc_dapm_widget *widgets[];

• struct snd_soc_dapm_widget *widgets[] __counted_by(num_widgets); };

  #define for_each_dapm_widgets(list, i, widget) \

diff --git a/sound/soc/soc-dapm.c b/sound/soc/soc-dapm.c index 2512aadf95f7..2e3df47c9cf3 100644 --- a/sound/soc/soc-dapm.c +++ b/sound/soc/soc-dapm.c @@ -497,8 +497,8 @@ static int dapm_kcontrol_add_widget(struct snd_kcontrol *kcontrol, if (!new_wlist) return -ENOMEM;

• new_wlist->widgets[n - 1] = widget; new_wlist->num_widgets = n;

• new_wlist->widgets[n - 1] = widget;

  data->wlist = new_wlist;