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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 B0BAEC32750 for ; Tue, 13 Aug 2019 09:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C354C20679 for ; Tue, 13 Aug 2019 09:30:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727817AbfHMJa4 (ORCPT ); Tue, 13 Aug 2019 05:30:56 -0400 Received: from michel.telenet-ops.be ([195.130.137.88]:39160 "EHLO michel.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726915AbfHMJa4 (ORCPT ); Tue, 13 Aug 2019 05:30:56 -0400 Received: from ramsan ([84.194.98.4]) by michel.telenet-ops.be with bizsmtp id oZWn2000Y05gfCL06ZWnvJ; Tue, 13 Aug 2019 11:30:54 +0200 Received: from rox.of.borg ([192.168.97.57]) by ramsan with esmtp (Exim 4.90_1) (envelope-from ) id 1hxT8h-0001Ef-Ny; Tue, 13 Aug 2019 11:30:47 +0200 Received: from geert by rox.of.borg with local (Exim 4.90_1) (envelope-from ) id 1hxT8h-0001Iz-KD; Tue, 13 Aug 2019 11:30:47 +0200 From: Geert Uytterhoeven To: Andrzej Pietrasiewicz , Neil Armstrong , Andrzej Hajda Cc: Laurent Pinchart , Jonas Karlman , Jernej Skrabec , David Airlie , Daniel Vetter , Guenter Roeck , Sam Ravnborg , Emil Velikov , dri-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH] drm/bridge: dumb-vga-dac: Fix dereferencing -ENODEV DDC channel Date: Tue, 13 Aug 2019 11:30:46 +0200 Message-Id: <20190813093046.4976-1-geert+renesas@glider.be> X-Mailer: git-send-email 2.17.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the VGA connector has no DDC channel, an error pointer will be dereferenced, e.g. on Salvator-XS: Unable to handle kernel NULL pointer dereference at virtual address 000000000000017d ... Call trace: sysfs_do_create_link_sd.isra.0+0x40/0x108 sysfs_create_link+0x20/0x40 drm_sysfs_connector_add+0xa8/0xc8 drm_connector_register.part.3+0x54/0xb0 drm_connector_register_all+0xb0/0xd0 drm_modeset_register_all+0x54/0x88 drm_dev_register+0x18c/0x1d8 rcar_du_probe+0xe4/0x150 ... This happens because vga->ddc either contains a valid DDC channel pointer, or -ENODEV, and drm_connector_init_with_ddc() expects a valid DDC channel pointer, or NULL. Fix this by resetting vga->ddc to NULL in case of -ENODEV, and replacing the existing error checks by non-NULL checks. This is similar to what the HDMI connector driver does. Fixes: a4f9087e85de141e ("drm/bridge: dumb-vga-dac: Provide ddc symlink in connector sysfs directory") Signed-off-by: Geert Uytterhoeven --- An alternative would be to check if vga->ddc contains an error pointer, and calling drm_connector_init() instead of drm_connector_init_with_ddc(), like before. --- drivers/gpu/drm/bridge/dumb-vga-dac.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/bridge/dumb-vga-dac.c b/drivers/gpu/drm/bridge/dumb-vga-dac.c index 8ef6539ae78a6eb3..7aa789c358829b05 100644 --- a/drivers/gpu/drm/bridge/dumb-vga-dac.c +++ b/drivers/gpu/drm/bridge/dumb-vga-dac.c @@ -42,7 +42,7 @@ static int dumb_vga_get_modes(struct drm_connector *connector) struct edid *edid; int ret; - if (IS_ERR(vga->ddc)) + if (!vga->ddc) goto fallback; edid = drm_get_edid(connector, vga->ddc); @@ -84,7 +84,7 @@ dumb_vga_connector_detect(struct drm_connector *connector, bool force) * wire the DDC pins, or the I2C bus might not be working at * all. */ - if (!IS_ERR(vga->ddc) && drm_probe_ddc(vga->ddc)) + if (vga->ddc && drm_probe_ddc(vga->ddc)) return connector_status_connected; return connector_status_unknown; @@ -197,6 +197,7 @@ static int dumb_vga_probe(struct platform_device *pdev) if (PTR_ERR(vga->ddc) == -ENODEV) { dev_dbg(&pdev->dev, "No i2c bus specified. Disabling EDID readout\n"); + vga->ddc = NULL; } else { dev_err(&pdev->dev, "Couldn't retrieve i2c bus\n"); return PTR_ERR(vga->ddc); @@ -218,7 +219,7 @@ static int dumb_vga_remove(struct platform_device *pdev) drm_bridge_remove(&vga->bridge); - if (!IS_ERR(vga->ddc)) + if (vga->ddc) i2c_put_adapter(vga->ddc); return 0; -- 2.17.1