Re: [PATCH 6/6] media: amlogic-c3: Add validations for ae and awb config

[Ricardo Ribalda]

Hi Laurent

On Tue, 28 Apr 2026 at 15:10, Laurent Pinchart
<laurent.pinchart@xxxxxxxxxxxxxxxx> wrote:
>
> Hi Ricardo,
>
> Thank you for the patch.
>
> CC'ing Jacopo.
>
> On Tue, Apr 28, 2026 at 12:41:12PM +0000, Ricardo Ribalda wrote:
> > Avoid invalid memory access if the zones_num is bigger than
> > zone_weight.
> >
> > This patch fixes the following smatch errors:
> > drivers/media/platform/amlogic/c3/isp/c3-isp-params.c:111 c3_isp_params_awb_wt() error: buffer overflow 'cfg->zone_weight' 768 <= u32max
> > drivers/media/platform/amlogic/c3/isp/c3-isp-params.c:111 c3_isp_params_awb_wt() error: buffer overflow 'cfg->zone_weight' 768 <= u32max
> > drivers/media/platform/amlogic/c3/isp/c3-isp-params.c:227 c3_isp_params_ae_wt() error: buffer overflow 'cfg->zone_weight' 255 <= u32max
> > drivers/media/platform/amlogic/c3/isp/c3-isp-params.c:227 c3_isp_params_ae_wt() error: buffer overflow 'cfg->zone_weight' 255 <= u32max
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> > ---
> >  drivers/media/platform/amlogic/c3/isp/c3-isp-params.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c b/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
> > index 6f9ca7a7dd88..42d780f684d1 100644
> > --- a/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
> > +++ b/drivers/media/platform/amlogic/c3/isp/c3-isp-params.c
> > @@ -104,6 +104,8 @@ static void c3_isp_params_awb_wt(struct c3_isp_device *isp,
> >       c3_isp_write(isp, ISP_AWB_BLK_WT_ADDR, 0);
> >
> >       zones_num = cfg->horiz_zones_num * cfg->vert_zones_num;
> > +     if (WARN_ON(zones_num > C3_ISP_AWB_MAX_ZONES))
>
> This is triggerable by userspace, it shouldn't result in a WARN_ON().
> Ideally the horiz_zones_num and vert_zones_num should be validated at
> buf prepare time, and an error should be returned to userspace. That
> will likely not fix your smatch issue though, I don't think it will be
> able to understand that the values have been validated.

Based on the warnings from the other drivers I also suspect that if
you have validated the data somewhere else smatch will understand it.

Even if you add a validate function I would suggest to keep the
WARN_ON(), ideally it should never trigger, and if it triggers it will
get a lot more attention to get it fixed.

>
> Jacopo, do we need to add a validate function pointer to
> v4l2_isp_params_block_type_info ?
>
> > +             zones_num = C3_ISP_AWB_MAX_ZONES;
> >
> >       /* Need to write 8 weights at once */
> >       for (i = 0; i < zones_num / 8; i++) {
> > @@ -220,6 +222,8 @@ static void c3_isp_params_ae_wt(struct c3_isp_device *isp,
> >       c3_isp_write(isp, ISP_AE_BLK_WT_ADDR, 0);
> >
> >       zones_num = cfg->horiz_zones_num * cfg->vert_zones_num;
> > +     if (WARN_ON(zones_num > C3_ISP_AE_MAX_ZONES))
> > +             zones_num = C3_ISP_AE_MAX_ZONES;
> >
> >       /* Need to write 8 weights at once */
> >       for (i = 0; i < zones_num / 8; i++) {
> >
>
> --
> Regards,
>
> Laurent Pinchart



-- 
Ricardo Ribalda