From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 93F89C43441 for ; Thu, 15 Nov 2018 23:07:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6199A2145D for ; Thu, 15 Nov 2018 23:07:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6199A2145D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=collabora.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389151AbeKPJRP (ORCPT ); Fri, 16 Nov 2018 04:17:15 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:47512 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725860AbeKPJRO (ORCPT ); Fri, 16 Nov 2018 04:17:14 -0500 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: sre) with ESMTPSA id DDE8F27E75C From: Sebastian Reichel To: Sebastian Reichel , Tomi Valkeinen , Tony Lindgren , Pavel Machek , Laurent Pinchart Cc: "H. Nikolaus Schaller" , dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, kernel@collabora.com, Sebastian Reichel Subject: [PATCHv4 4/6] drm/omap: fix incorrect union usage Date: Fri, 16 Nov 2018 00:06:43 +0100 Message-Id: <20181115230645.15748-5-sebastian.reichel@collabora.com> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20181115230645.15748-1-sebastian.reichel@collabora.com> References: <20181115230645.15748-1-sebastian.reichel@collabora.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The DSI encoder sets dssdev->ops->dsi.set_config, which is stored at the same offset as dssdev->ops->hdmi.set_hdmi_mode. The code in omap_encoder only checks if dssdev->ops->hdmi.set_hdmi_mode is NULL. Due to the way union works, it won't be NULL if dsi.set_config is set. This means dsi_set_config will be called with config=hdmi_mode=false=NULL parameter resulting in a NULL dereference. Also the dereference happens while console is locked, so kernel hangs without any debug output (can be avoided by fbmem's lockless_register_fb=1 parameter). This fixes the issue by exiting early if the output type definitely has no hdmi_set operations. Fixes: 83910ad3f51fb ("drm/omap: Move most omap_dss_driver operations to omap_dss_device_ops") Signed-off-by: Sebastian Reichel --- drivers/gpu/drm/omapdrm/omap_encoder.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/gpu/drm/omapdrm/omap_encoder.c b/drivers/gpu/drm/omapdrm/omap_encoder.c index 32bbe3a80e7d..ba0099f0644c 100644 --- a/drivers/gpu/drm/omapdrm/omap_encoder.c +++ b/drivers/gpu/drm/omapdrm/omap_encoder.c @@ -122,6 +122,14 @@ static void omap_encoder_mode_set(struct drm_encoder *encoder, dssdev = omap_encoder->output; + /* The following operations access dssdev->ops->hdmi, which is a union + * also used by DSI. This ensures, that the field does not have data + * for DSI (or any other future output type). + */ + if (dssdev->output_type != OMAP_DISPLAY_TYPE_HDMI && + dssdev->output_type != OMAP_DISPLAY_TYPE_DVI) + return; + if (dssdev->ops->hdmi.set_hdmi_mode) dssdev->ops->hdmi.set_hdmi_mode(dssdev, hdmi_mode); -- 2.19.1