int drm_mode_dirtyfb_ioctl(struct drm_device *dev,
			   void *data, struct drm_file *file_priv)
{
	struct drm_clip_rect __user *clips_ptr;
	struct drm_clip_rect *clips = NULL;
	struct drm_mode_fb_dirty_cmd *r = data;
	struct drm_mode_object *obj;
	struct drm_framebuffer *fb;
	unsigned flags;
	int num_clips;
	int ret = 0;

	if (!drm_core_check_feature(dev, DRIVER_MODESET))
		return -EINVAL;

	mutex_lock(&dev->mode_config.mutex);
	obj = drm_mode_object_find(dev, r->fb_id, DRM_MODE_OBJECT_FB);
	if (!obj) {
		DRM_ERROR("invalid framebuffer id\n");
		ret = -EINVAL;
		goto out_err1;
	}
	fb = obj_to_fb(obj);

	num_clips = r->num_clips;
	clips_ptr = (struct drm_clip_rect *)(unsigned long)r->clips_ptr;

	if (!num_clips != !clips_ptr) {
		ret = -EINVAL;
		goto out_err1;
	}

	flags = DRM_MODE_FB_DIRTY_FLAGS & r->flags;

	/* If userspace annotates copy, clips must come in pairs */
	if (flags & DRM_MODE_FB_DIRTY_ANNOTATE_COPY && (num_clips % 2)) {
		ret = -EINVAL;
		goto out_err1;
	}

	if (num_clips && clips_ptr) {
		if (num_clips < 0 || num_clips > DRM_MODE_FB_DIRTY_MAX_CLIPS) {
			ret = -EINVAL;
			goto out_err1;
		}
		clips = kzalloc(num_clips * sizeof(*clips), GFP_KERNEL);
		if (!clips) {
			ret = -ENOMEM;
			goto out_err1;
		}

		ret = copy_from_user(clips, clips_ptr,
				     num_clips * sizeof(*clips));
		if (ret) {
			ret = -EFAULT;
			goto out_err2;
		}
	}

	if (fb->funcs->dirty) {
		ret = fb->funcs->dirty(fb, file_priv, flags, r->color,
				       clips, num_clips);
	} else {
		ret = -ENOSYS;
		goto out_err2;
	}

out_err2:
	kfree(clips);
out_err1:
	mutex_unlock(&dev->mode_config.mutex);
	return ret;
}
The software performs a calculation that can produce an integer overflow or wraparound, when the logic assumes that the resulting value will always be larger than the original value. This can introduce other weaknesses when the calculation is used for resource management or execution control.