On Fri, Nov 22, 2019 at 07:56:20PM +0200, Ville Syrjala wrote:

From: Ville Syrjälä ville.syrjala@linux.intel.com

Check for zero width/height destination rectangle in drm_rect_clip_scaled() to avoid a division by zero.

Cc: stable@vger.kernel.org Fixes: f96bdf564f3e ("drm/rect: Handle rounding errors in drm_rect_clip_scaled, v3.") Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com Cc: Benjamin Gaignard benjamin.gaignard@st.com Cc: Daniel Vetter daniel@ffwll.ch Testcase: igt/kms_selftest/drm_rect_clip_scaled_div_by_zero Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com

Clamping src to 0 if dst is 0 makes sense to me.

Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch

---

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