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From:   sun yq <yqsun1997@gmail.com>
Date:   Wed, 28 Jun 2023 18:09:22 +0800
Message-ID: <CAA0BgY_1Rn4LJ4NM7ZMNgG1K-V9Uy0HTi6bMg_o3cPDWj7NfKQ@mail.gmail.com>
Subject: Re: [PATCH] OOB read and write in mdp_prepare_buffer
To:     sun yq <yqsun1997@gmail.com>, mchehab@kernel.org,
        matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org, 499671216@qq.com
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Hi Alain,

May I ask if you are the person involved in the code?We should  listen
to the opinions of the code owner.

On Wed, Jun 28, 2023 at 2:34=E2=80=AFPM Alain Volmat <alain.volmat@foss.st.=
com> wrote:
>
> Hi,
>
> On Wed, Jun 28, 2023 at 07:28:54AM +0800, sun yq wrote:
> > Hi,
> > Because there are many functions using the plane, increasing the max
> > number of the plane is to maximize the solution to all possible oob
> > places.
>
> I don't think it is the right approach then.  If the HW is only handling
> 3 planes, there should be no reason to have to allocate for 8 planes.  I
> suspect that this 8 value is coming from the maximum allowed plane
> number in V4L2 right ?
> INHO driver should simply be fixed to ensure that num_plane won't go
> higher than the real number of plane allocated in the structures.
> It should be possible to get the num_plane value from the format
> selected.
>
> Alain
>
> >
> > On Tue, Jun 27, 2023 at 10:06=E2=80=AFPM Alain Volmat <alain.volmat@fos=
s.st.com> wrote:
> > >
> > > Hi,
> > >
> > > On Tue, Jun 27, 2023 at 04:27:31PM +0800, yqsun1997@gmail.com wrote:
> > > > From: yqsun1997 <yqsun1997@gmail.com>
> > > >
> > > > Because format in struct img_image_buffer max index is IMG_MAX_PLAN=
ES =3D=3D3,
> > > > The num_planes max index is 8.so will be OOB like in mdp_prepare_bu=
ffer.
> > >
> > > Similarly as your other patch, could you describe why you need to
> > > increase the IMG_MAX_PLANES while I suspect your driver only needs to
> > > deal with 3 planes.  While the maximum num_planes value that can be
> > > given by the user is 8, this has to be first compared to the configur=
ed
> > > format prior to reaching this function.
> > >
> > > >
> > > > static void mdp_prepare_buffer(struct img_image_buffer *b,
> > > >                                struct mdp_frame *frame, struct vb2_=
buffer *vb)
> > > > {
> > > >         struct v4l2_pix_format_mplane *pix_mp =3D &frame->format.fm=
t.pix_mp;
> > > >         unsigned int i;
> > > >
> > > >         b->format.colorformat =3D frame->mdp_fmt->mdp_color;
> > > >         b->format.ycbcr_prof =3D frame->ycbcr_prof;
> > > >         for (i =3D 0; i < pix_mp->num_planes; ++i) {
> > > >                 u32 stride =3D mdp_fmt_get_stride(frame->mdp_fmt,
> > > >                         pix_mp->plane_fmt[i].bytesperline, i);
> > > >
> > > >                 b->format.plane_fmt[i].stride =3D stride;  //oob
> > > >                 ......
> > > >
> > > > Signed-off-by: yqsun1997 <yqsun1997@gmail.com>
> > > > ---
> > > >  drivers/media/platform/mediatek/mdp3/mtk-mdp3-type.h | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-type.h b=
/drivers/media/platform/mediatek/mdp3/mtk-mdp3-type.h
> > > > index ae0396806..e2e991a34 100644
> > > > --- a/drivers/media/platform/mediatek/mdp3/mtk-mdp3-type.h
> > > > +++ b/drivers/media/platform/mediatek/mdp3/mtk-mdp3-type.h
> > > > @@ -11,7 +11,7 @@
> > > >
> > > >  #define IMG_MAX_HW_INPUTS    3
> > > >  #define IMG_MAX_HW_OUTPUTS   4
> > > > -#define IMG_MAX_PLANES               3
> > > > +#define IMG_MAX_PLANES               8
> > > >  #define IMG_MAX_COMPONENTS   20
> > > >
> > > >  struct img_crop {
> > > > --
> > > > 2.39.2
> > > >
> > >
> > > Regards,
> > > Alain