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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

On Tue, Apr 28, 2026 at 03:14:21PM +0200, Ricardo Ribalda wrote:
> On Tue, 28 Apr 2026 at 15:10, Laurent Pinchart wrote:
> > 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@chromium.org>
> > > ---
> > >  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.

We could keep the WARN_ON() if we first validate the data, but the
driver doesn't currently :-/ I expect there could be more similar
issues.

> > 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