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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 C50A9C433C1 for ; Sun, 21 Mar 2021 05:52:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8E2AD61929 for ; Sun, 21 Mar 2021 05:52:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230063AbhCUFwK (ORCPT ); Sun, 21 Mar 2021 01:52:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52120 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230002AbhCUFvr (ORCPT ); Sun, 21 Mar 2021 01:51:47 -0400 Received: from mail-qt1-x82a.google.com (mail-qt1-x82a.google.com [IPv6:2607:f8b0:4864:20::82a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 69C60C061574; Sat, 20 Mar 2021 22:51:47 -0700 (PDT) Received: by mail-qt1-x82a.google.com with SMTP id l13so10005412qtu.9; Sat, 20 Mar 2021 22:51:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=6awWR6J01S3VvaFl3l226JcCIWl910GFIDAp2HokN38=; b=QfSc/Hmcj8RYWcukNSs5oJtHP2rBqciQFojqJRMh6+2MmKoJQXWQQezTv1iIdaoa+H 9dHDCJBi0i8woUgns9Pdq/K3BaAghbaojHycO3qsOshhmP3dL577Z1zgRl2CfjwziExu 4ANF1fR45LA8yeESbxi1l9ZbSk3hnoIoc4kW/5qwFiBJcyF+pdG98Pa6p0EYiS6+0mR8 hZNYVMiaHG2FE4XhrD6ClFUaOCmLDEvHFnS51q8zK3jLHvctMUSwFRfovmnRVDy9D13p 55l2fY1IteMLVTDSs8KM7oarbwFxjOFuWrfSw1Pht4AfdV8N2ybkwL6K3/QryNVijTAi ggXg== 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:mime-version :content-transfer-encoding; bh=6awWR6J01S3VvaFl3l226JcCIWl910GFIDAp2HokN38=; b=M3LL2qvBPW33t7mzQK5HLsPik4ckL9EtXmgLpOb7PXSlISzMh5fOvAM5ZoZjd9przk jZCwgkSQVEX+TypgKPNOOIQ6SRbGvVQM8vU9yDJQMeFuVHpeeLQqV8TwN/eoPRgc5AEF 73DYqp4mvAxjW5w6aoOCU914wrMaoCoIuSDG00pR4ArGfWWOJ5w4IxIx2ZJ3d8K2PaFQ aOyU/bdmaZpUB1KKuhSv/pmeR+Oq1mNIX/qar+qw9+KPGDsmqIbYHmsqq8KAW6qbF9ti H5h38VAJKRS4rKhTQa2bM4NYNb9olY3dK/IudtiHVVGmi3FZW/lfsKoeP8x007Sgl5Ft WFJA== X-Gm-Message-State: AOAM533H9bKykexhgd9v1UU2GlpqlkJ2L1I/brbt7RO9LwtnQqjU557R BWSGdccs2VWR/bzX4I3bshw= X-Google-Smtp-Source: ABdhPJySkkAFeiAd27mDgmoUE9tw3W94rJaHOLPZBbRrst+ymaFnUzDlKMhjico51M13z2959Urs6g== X-Received: by 2002:a05:622a:293:: with SMTP id z19mr4905508qtw.309.1616305906600; Sat, 20 Mar 2021 22:51:46 -0700 (PDT) Received: from tong-desktop.local ([2601:5c0:c200:27c6:f925:bb4b:54d2:533]) by smtp.googlemail.com with ESMTPSA id n77sm8359502qkn.128.2021.03.20.22.51.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 20 Mar 2021 22:51:46 -0700 (PDT) From: Tong Zhang To: Scott Murray , Bjorn Helgaas , linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Tong Zhang Subject: [PATCH] PCI: hotplug: fix null-ptr-dereferencd in cpcihp error path Date: Sun, 21 Mar 2021 01:51:08 -0400 Message-Id: <20210321055109.322496-1-ztong0001@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There is an issue in the error path, which cpci_thread may remain NULL. Calling kthread_stop(cpci_thread) will trigger a BUG(). It is better to check whether the thread is really created and started before stop it. [ 1.292859] BUG: kernel NULL pointer dereference, address: 0000000000000028 [ 1.293252] #PF: supervisor write access in kernel mode [ 1.293533] #PF: error_code(0x0002) - not-present page [ 1.295163] RIP: 0010:kthread_stop+0x22/0x170 [ 1.300491] Call Trace: [ 1.300628] cpci_hp_unregister_controller+0xf6/0x130 [ 1.300906] zt5550_hc_init_one+0x27a/0x27f [cpcihp_zt5550] Signed-off-by: Tong Zhang --- drivers/pci/hotplug/cpci_hotplug_core.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/pci/hotplug/cpci_hotplug_core.c b/drivers/pci/hotplug/cpci_hotplug_core.c index d0559d2faf50..b44da397d631 100644 --- a/drivers/pci/hotplug/cpci_hotplug_core.c +++ b/drivers/pci/hotplug/cpci_hotplug_core.c @@ -47,7 +47,7 @@ static atomic_t extracting; int cpci_debug; static struct cpci_hp_controller *controller; static struct task_struct *cpci_thread; -static int thread_finished; +static int thread_started; static int enable_slot(struct hotplug_slot *slot); static int disable_slot(struct hotplug_slot *slot); @@ -447,7 +447,7 @@ event_thread(void *data) msleep(500); } else if (rc < 0) { dbg("%s - error checking slots", __func__); - thread_finished = 1; + thread_started = 0; goto out; } } while (atomic_read(&extracting) && !kthread_should_stop()); @@ -479,7 +479,7 @@ poll_thread(void *data) msleep(500); } else if (rc < 0) { dbg("%s - error checking slots", __func__); - thread_finished = 1; + thread_started = 0; goto out; } } while (atomic_read(&extracting) && !kthread_should_stop()); @@ -501,7 +501,7 @@ cpci_start_thread(void) err("Can't start up our thread"); return PTR_ERR(cpci_thread); } - thread_finished = 0; + thread_started = 1; return 0; } @@ -509,7 +509,7 @@ static void cpci_stop_thread(void) { kthread_stop(cpci_thread); - thread_finished = 1; + thread_started = 0; } int @@ -571,7 +571,7 @@ cpci_hp_unregister_controller(struct cpci_hp_controller *old_controller) int status = 0; if (controller) { - if (!thread_finished) + if (thread_started) cpci_stop_thread(); if (controller->irq) free_irq(controller->irq, controller->dev_id); -- 2.25.1