[PATCH] drm/i915:fix the overflow for overlay when crtc_w or crtc_h =0

[Hai Lan]

When the crtc_w = 0 or crtc_h = 0, it should not be divided.
Besides, when (crtc_x+<crtc_w)<0 or (crtc_y+crtc_h)<0, it should be handled.

Signed-off-by: Hai Lan <hai.lan at intel.com>
---
 drivers/gpu/drm/i915/intel_sprite.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_sprite.c 
b/drivers/gpu/drm/i915/intel_sprite.c
index 0891bda..d62e8ca 100644
--- a/drivers/gpu/drm/i915/intel_sprite.c
+++ b/drivers/gpu/drm/i915/intel_sprite.c
@@ -268,17 +268,23 @@ intel_update_plane(struct drm_plane *plane, struct 
drm_crtc *crtc,
         * try to scale the source if part of the visible region is offscreen.
         * The caller must handle that by adjusting source offset and size.
         */
-       if (crtc_x < 0) {
+       if ((crtc_x < 0) && ((crtc_x + crtc_w)>0)) {
                crtc_w += crtc_x;
                crtc_x = 0;
        }
+       if ((crtc_x + crtc_w)<0) {
+               return -EINVAL;
+       }
        if (crtc_x + crtc_w > primary_w)
                crtc_w = primary_w - crtc_x;

-       if (crtc_y < 0) {
+       if ((crtc_y < 0) && ((crtc_y+crtc_h)>0)) {
                crtc_h += crtc_y;
                crtc_y = 0;
        }
+       if ((crtc_y+crtc_h)<0) {
+               return -EINVAL;
+       }
        if (crtc_y + crtc_h > primary_h)
                crtc_h = primary_h - crtc_y;

@@ -286,7 +292,9 @@ intel_update_plane(struct drm_plane *plane, struct drm_crtc 
*crtc,
         * We can take a larger source and scale it down, but
         * only so much...  16x is the max on SNB.
         */
-       if (((src_w * src_h) / (crtc_w * crtc_h)) > intel_plane->max_downscale)
+       if (crtc_w == 0 || crtc_h == 0)
+               return -EINVAL;
+       else if (((src_w * src_h) / (crtc_w * crtc_h)) > 
intel_plane->max_downscale)
                return -EINVAL;

        /*
-- 
1.7.4.1