drm/i915/overlay: Prevent divide by zero bugs in scaling

Smatch detected a divide by zero bug in check_overlay_scaling().

    drivers/gpu/drm/i915/display/intel_overlay.c:976 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_height'.
    drivers/gpu/drm/i915/display/intel_overlay.c:980 check_overlay_scaling()
    error: potential divide by zero bug '/ rec->dst_width'.

Prevent this by ensuring that the dst height and width are non-zero.

Fixes: 02e792fbaadb ("drm/i915: implement drmmode overlay support v4")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20220124122409.GA31673@kili
(cherry picked from commit cf5b64f7f10b28bebb9b7c9d25e7aee5cbe43918)
Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_overlay.c b/drivers/gpu/drm/i915/display/intel_overlay.c
index 1a376e9..d610e48 100644 (file)
--- a/drivers/gpu/drm/i915/display/intel_overlay.c
+++ b/drivers/gpu/drm/i915/display/intel_overlay.c
@@ -959,6 +959,9 @@ static int check_overlay_dst(struct intel_overlay *overlay,
        const struct intel_crtc_state *pipe_config =
                overlay->crtc->config;
 
+       if (rec->dst_height == 0 || rec->dst_width == 0)
+               return -EINVAL;
+
        if (rec->dst_x < pipe_config->pipe_src_w &&
            rec->dst_x + rec->dst_width <= pipe_config->pipe_src_w &&
            rec->dst_y < pipe_config->pipe_src_h &&