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=-3.9 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 331C1C65BAF for ; Sun, 9 Dec 2018 22:22:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01EE820661 for ; Sun, 9 Dec 2018 22:22:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01EE820661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=decadent.org.uk 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 S1728321AbeLIWWF (ORCPT ); Sun, 9 Dec 2018 17:22:05 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:35190 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726517AbeLIVzV (ORCPT ); Sun, 9 Dec 2018 16:55:21 -0500 Received: from pub.yeoldevic.com ([81.174.156.145] helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1gW72k-0002pr-6i; Sun, 09 Dec 2018 21:55:18 +0000 Received: from ben by deadeye with local (Exim 4.91) (envelope-from ) id 1gW72h-0003Yn-IB; Sun, 09 Dec 2018 21:55:15 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Daniel Vetter" , "Sean Paul" , "Emil Lundmark" Date: Sun, 09 Dec 2018 21:50:33 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 230/328] drm: udl: Destroy framebuffer only if it was initialized In-Reply-To: X-SA-Exim-Connect-IP: 81.174.156.145 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.62-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Emil Lundmark commit fcb74da1eb8edd3a4ef9b9724f88ed709d684227 upstream. This fixes a NULL pointer dereference that can happen if the UDL driver is unloaded before the framebuffer is initialized. This can happen e.g. if the USB device is unplugged right after it was plugged in. As explained by Stéphane Marchesin: It happens when fbdev is disabled (which is the case for Chrome OS). Even though intialization of the fbdev part is optional (it's done in udlfb_create which is the callback for fb_probe()), the teardown isn't optional (udl_driver_unload -> udl_fbdev_cleanup -> udl_fbdev_destroy). Note that udl_fbdev_cleanup *tries* to be conditional (you can see it does if (!udl->fbdev)) but that doesn't work, because udl->fbdev is always set during udl_fbdev_init. Suggested-by: Sean Paul Reviewed-by: Sean Paul Acked-by: Daniel Vetter Signed-off-by: Emil Lundmark Signed-off-by: Sean Paul Link: https://patchwork.freedesktop.org/patch/msgid/20180528142711.142466-1-lndmrk@chromium.org Signed-off-by: Sean Paul [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings --- drivers/gpu/drm/udl/udl_fb.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/drivers/gpu/drm/udl/udl_fb.c +++ b/drivers/gpu/drm/udl/udl_fb.c @@ -574,9 +574,11 @@ static void udl_fbdev_destroy(struct drm framebuffer_release(info); } drm_fb_helper_fini(&ufbdev->helper); - drm_framebuffer_unregister_private(&ufbdev->ufb.base); - drm_framebuffer_cleanup(&ufbdev->ufb.base); - drm_gem_object_unreference_unlocked(&ufbdev->ufb.obj->base); + if (ufbdev->ufb.obj) { + drm_framebuffer_unregister_private(&ufbdev->ufb.base); + drm_framebuffer_cleanup(&ufbdev->ufb.base); + drm_gem_object_unreference_unlocked(&ufbdev->ufb.obj->base); + } } int udl_fbdev_init(struct drm_device *dev)