[PATCH] media: nxp: isi: Check whether pad is non-NULL before access

[Kieran Bingham]

Quoting Laurent Pinchart (2023-12-03 16:59:59)
> Hi Marek,
> 
> Thank you for the patch.
> 
> On Fri, Dec 01, 2023 at 04:06:04PM +0100, Marek Vasut wrote:
> > The pad can be NULL if media controller routing is not set up correctly.
> > Check whether the pad is NULL before using it, otherwise it is possible
> > to achieve NULL pointer dereference.
> 
> Could you share more information about how to misconfigure the routing ?

You simply do 'nothing'.

--
Kieran


> 
> > Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
> > Signed-off-by: Marek Vasut <marex at denx.de>
> > ---
> > Cc: Fabio Estevam <festevam at gmail.com>
> > Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> > Cc: Mauro Carvalho Chehab <mchehab at kernel.org>
> > Cc: NXP Linux Team <linux-imx at nxp.com>
> > Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> > Cc: Sascha Hauer <s.hauer at pengutronix.de>
> > Cc: Shawn Guo <shawnguo at kernel.org>
> > Cc: linux-arm-kernel at lists.infradead.org
> > Cc: linux-media at vger.kernel.org
> > ---
> >  drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c | 8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > index 792f031e032ae..44354931cf8a1 100644
> > --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> > @@ -160,8 +160,14 @@ mxc_isi_crossbar_xlate_streams(struct mxc_isi_crossbar *xbar,
> >       }
> >  
> >       pad = media_pad_remote_pad_first(&xbar->pads[sink_pad]);
> > -     sd = media_entity_to_v4l2_subdev(pad->entity);
> > +     if (!pad) {
> > +             dev_dbg(xbar->isi->dev,
> > +                     "no pad connected to crossbar input %u\n",
> > +                     sink_pad);
> > +             return ERR_PTR(-EPIPE);
> > +     }
> >  
> > +     sd = media_entity_to_v4l2_subdev(pad->entity);
> >       if (!sd) {
> >               dev_dbg(xbar->isi->dev,
> >                       "no entity connected to crossbar input %u\n",
> 
> -- 
> Regards,
> 
> Laurent Pinchart