From patchwork Sat Oct 31 00:37:21 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Stultz X-Patchwork-Id: 314291 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=-12.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 9ACA3C4742C for ; Sat, 31 Oct 2020 00:37:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5259220702 for ; Sat, 31 Oct 2020 00:37:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="bRnUkU5Q" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725959AbgJaAha (ORCPT ); Fri, 30 Oct 2020 20:37:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44786 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725960AbgJaAh3 (ORCPT ); Fri, 30 Oct 2020 20:37:29 -0400 Received: from mail-pg1-x544.google.com (mail-pg1-x544.google.com [IPv6:2607:f8b0:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C1BDEC0613D5 for ; Fri, 30 Oct 2020 17:37:27 -0700 (PDT) Received: by mail-pg1-x544.google.com with SMTP id g12so6540957pgm.8 for ; Fri, 30 Oct 2020 17:37:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=hvoWVjH5MrvJlNL+Wpvlrvtr/qdzZEjizkDpZ+3TUPw=; b=bRnUkU5QJDdovKB+3Oe64UD9XdGDPdwmEL0e6homqfsQ1GrFivNaT1ceK4jr1G1+hD Xbxz4vWZTuO7moh7D/gW1/RgAf7UfMkBg5sT/9tzH5t5cDLLDpZNgMsiPjipAuG9JU9a /oJaZOVt49Hshtnxjyt3fN+2HhvC0sdg9XYHDTDLnfWn+9GFau6SbOzuehTkD9sXpeyz QlOOZ+vBKupPhbBvtMsR2abFGbElx1JBNuqPQLrDA9LsFD3PRpg7o6cZ3fdIr5sdZqZ0 TkQ+0OvYEwaPH/hljQjozd5Ynr4RR/vYgr5LS3ISaJs/vgJmazLuhn6jX01hFMa3nbZm s4Ew== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=hvoWVjH5MrvJlNL+Wpvlrvtr/qdzZEjizkDpZ+3TUPw=; b=rvxCr5xLkz8okW/HptaN7hUqTqMl0scz6p+4FdmnsOKxCXERbkBIeIQ5QMQrVoypLO og/CGhd4q+xfVVvq1fbsQ4tV5w/OfGeEhEPTwfFZqRoe6VbxQaSzooHswKmx8ioeNNI1 8LMULoD74GZ1NXiRHy5YuEKWDBFKG/Y8ddtcArziCx4K+KRCsxScpNTeIawlmNEpv1Rz bK0e5AZ4zXL7pTrse9S/YzU/pCyIyEnqKDcFUHv/qhA/KdDKjrM9rCAkUO3cRR+/4/Il vucpFexWPW8d1mxr7n173UWt1q8X8E09Gqz/FlVv5L2sHp4DniOIXK+yPVPo+3mT3UZ8 v+rQ== X-Gm-Message-State: AOAM530g2xCq0MGgs0wM/sBvgXboTFPSzKSesHOThi6uMIj/AkUU7X/9 FD3FjwvWv4YOtrN0tXQEVwRWXQ== X-Google-Smtp-Source: ABdhPJxeqhaBAC7zYRx5xaemqM+o7fL8zXijASb2rLhquYgoiO/uJc+BWuRhrzTtrM6vCX+g3MXc8A== X-Received: by 2002:aa7:9095:0:b029:164:75c4:5d15 with SMTP id i21-20020aa790950000b029016475c45d15mr11561202pfa.49.1604104647290; Fri, 30 Oct 2020 17:37:27 -0700 (PDT) Received: from localhost.localdomain ([2601:1c2:680:1319:692:26ff:feda:3a81]) by smtp.gmail.com with ESMTPSA id 3sm7011935pfv.92.2020.10.30.17.37.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2020 17:37:26 -0700 (PDT) From: John Stultz To: lkml Cc: John Stultz , Robin Murphy , Will Deacon , Andy Gross , Maulik Shah , Bjorn Andersson , Saravana Kannan , Marc Zyngier , Lina Iyer , iommu@lists.linux-foundation.org, linux-arm-msm Subject: [RFC][PATCH 2/2] iommu: Avoid crash if iommu_group is null Date: Sat, 31 Oct 2020 00:37:21 +0000 Message-Id: <20201031003721.40973-2-john.stultz@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201031003721.40973-1-john.stultz@linaro.org> References: <20201031003721.40973-1-john.stultz@linaro.org> Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org In trying to handle a possible driver probe ordering issue brought up by Robin Murphy, I ran across a separate null pointer crash in the iommu core in iommu_group_remove_device(): [ 2.732803] dwc3-qcom a6f8800.usb: failed to get usb-ddr path: -517 [ 2.739281] Unable to handle kernel NULL pointer dereference at virtual address 00000000000000c0 ... [ 2.775619] [00000000000000c0] user address but active_mm is swapper [ 2.782039] Internal error: Oops: 96000005 [#1] PREEMPT SMP [ 2.787670] Modules linked in: [ 2.790769] CPU: 6 PID: 1 Comm: swapper/0 Tainted: G W 5.10.0-rc1-mainline-00025-g272a618fc36-dirty #3973 [ 2.801719] Hardware name: Thundercomm Dragonboard 845c (DT) [ 2.807431] pstate: 00c00005 (nzcv daif +PAN +UAO -TCO BTYPE=--) [ 2.813508] pc : iommu_group_remove_device+0x30/0x1b0 [ 2.818611] lr : iommu_release_device+0x4c/0x78 [ 2.823189] sp : ffffffc01005b950 ... [ 2.907082] Call trace: [ 2.909566] iommu_group_remove_device+0x30/0x1b0 [ 2.914323] iommu_release_device+0x4c/0x78 [ 2.918559] iommu_bus_notifier+0xe8/0x108 [ 2.922708] blocking_notifier_call_chain+0x78/0xb8 [ 2.927641] device_del+0x2ac/0x3d0 [ 2.931177] platform_device_del.part.9+0x20/0x98 [ 2.935933] platform_device_unregister+0x2c/0x40 [ 2.940694] of_platform_device_destroy+0xd8/0xe0 [ 2.945450] device_for_each_child_reverse+0x58/0xb0 [ 2.950471] of_platform_depopulate+0x4c/0x78 [ 2.954886] dwc3_qcom_probe+0x93c/0xcb8 [ 2.958858] platform_drv_probe+0x58/0xa8 [ 2.962917] really_probe+0xec/0x398 [ 2.966531] driver_probe_device+0x5c/0xb8 [ 2.970677] device_driver_attach+0x74/0x98 [ 2.974911] __driver_attach+0x60/0xe8 [ 2.978700] bus_for_each_dev+0x84/0xd8 [ 2.982581] driver_attach+0x30/0x40 [ 2.986194] bus_add_driver+0x160/0x208 [ 2.990076] driver_register+0x64/0x110 [ 2.993957] __platform_driver_register+0x58/0x68 [ 2.998716] dwc3_qcom_driver_init+0x20/0x28 [ 3.003041] do_one_initcall+0x6c/0x2d0 [ 3.006925] kernel_init_freeable+0x214/0x268 [ 3.011339] kernel_init+0x18/0x118 [ 3.014876] ret_from_fork+0x10/0x18 [ 3.018495] Code: d0006a21 f9417295 91130021 910162b6 (b940c2a2) In the case above, the arm-smmu driver fails to probe with EPROBE_DEFER, and I'm guessing I'm guessing that causes iommu_group_add_device() to fail and sets the dev->iommu_group = NULL, then somehow we hit iommu_group_remove_device() and trip over the null value? I'm not really sure... Anyway, adding the null check seems to avoid the issue and the system boots fine after the arm-smmu driver later reprobed. Feedback or better ideas for a solution would be appreciated! Cc: Robin Murphy Cc: Will Deacon Cc: Andy Gross Cc: Maulik Shah Cc: Bjorn Andersson Cc: Saravana Kannan Cc: Marc Zyngier Cc: Lina Iyer Cc: iommu@lists.linux-foundation.org Cc: linux-arm-msm Signed-off-by: John Stultz --- drivers/iommu/iommu.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c index 8c470f451a323..44639b88e77db 100644 --- a/drivers/iommu/iommu.c +++ b/drivers/iommu/iommu.c @@ -877,6 +877,10 @@ void iommu_group_remove_device(struct device *dev) struct iommu_group *group = dev->iommu_group; struct group_device *tmp_device, *device = NULL; + /* Avoid crash if iommu_group value is null */ + if (!group) + return; + dev_info(dev, "Removing from iommu group %d\n", group->id); /* Pre-notify listeners that a device is being removed. */