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SubjectRe: [PATCH] OOB read and write in mdp_prepare_buffer
From
Hi!

On 6/27/23 10:27, yqsun1997@gmail.com wrote:
> From: yqsun1997 <yqsun1997@gmail.com>
>
> Because format in struct img_image_buffer max index is IMG_MAX_PLANES ==3,
> The num_planes max index is 8.so will be OOB like in mdp_prepare_buffer.
>
> 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 = &frame->format.fmt.pix_mp;
> unsigned int i;
>
> b->format.colorformat = frame->mdp_fmt->mdp_color;
> b->format.ycbcr_prof = frame->ycbcr_prof;
> for (i = 0; i < pix_mp->num_planes; ++i) {

Unless there is a bug in the driver, pix_mp->num_planes will never
exceed 3. Userspace might certainly pass more than 3 planes, but only
the first pix_mp->num_planes should ever be used.

If pix_mp->num_planes can ever be more than 3, then that would be the
real bug.

Regards,

Hans

> u32 stride = mdp_fmt_get_stride(frame->mdp_fmt,
> pix_mp->plane_fmt[i].bytesperline, i);
>
> b->format.plane_fmt[i].stride = 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 {

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