On Fri, Nov 22, 2019 at 07:56:20PM +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>
> Check for zero width/height destination rectangle in
> drm_rect_clip_scaled() to avoid a division by zero.
>
> Cc: stable@xxxxxxxxxxxxxxx
> Fixes: f96bdf564f3e ("drm/rect: Handle rounding errors in drm_rect_clip_scaled, v3.")
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxx>
> Cc: Daniel Vetter <daniel@xxxxxxxx>
> Testcase: igt/kms_selftest/drm_rect_clip_scaled_div_by_zero
> Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
Clamping src to 0 if dst is 0 makes sense to me.
Reviewed-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
> ---
> drivers/gpu/drm/drm_rect.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_rect.c b/drivers/gpu/drm/drm_rect.c
> index b8363aaa9032..818738e83d06 100644
> --- a/drivers/gpu/drm/drm_rect.c
> +++ b/drivers/gpu/drm/drm_rect.c
> @@ -54,7 +54,12 @@ EXPORT_SYMBOL(drm_rect_intersect);
>
> static u32 clip_scaled(u32 src, u32 dst, u32 clip)
> {
> - u64 tmp = mul_u32_u32(src, dst - clip);
> + u64 tmp;
> +
> + if (dst == 0)
> + return 0;
> +
> + tmp = mul_u32_u32(src, dst - clip);
>
> /*
> * Round toward 1.0 when clipping so that we don't accidentally
> --
> 2.23.0
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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