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=-11.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 C393EC41604 for ; Wed, 7 Oct 2020 17:24:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6C870215A4 for ; Wed, 7 Oct 2020 17:24:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727954AbgJGRY6 (ORCPT ); Wed, 7 Oct 2020 13:24:58 -0400 Received: from mga06.intel.com ([134.134.136.31]:19743 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726348AbgJGRY6 (ORCPT ); Wed, 7 Oct 2020 13:24:58 -0400 IronPort-SDR: 8gqoJfdp9w6OF3hUhtDeu/a6+wQ0u1kCavENw68I3CzOuNYgHn7WhrnoJ9nqMubu72KulUecj4 EVNz2Ym8vteA== X-IronPort-AV: E=McAfee;i="6000,8403,9767"; a="226640674" X-IronPort-AV: E=Sophos;i="5.77,347,1596524400"; d="scan'208";a="226640674" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga104.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2020 10:24:42 -0700 IronPort-SDR: b9zOkwa7LvyHbSC5Eh+2GttwP0Db6g8aVUBH+EwWdVmDE6fIsB6HBW0/T0EjblCu8IJq8GQTy+ pY/rV66xjD0Q== X-IronPort-AV: E=Sophos;i="5.77,347,1596524400"; d="scan'208";a="311833132" Received: from jdelcan-mobl.amr.corp.intel.com (HELO [10.254.64.135]) ([10.254.64.135]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 07 Oct 2020 10:24:42 -0700 Subject: Re: [PATCH v8 1/6] PCI/ERR: get device before call device driver to avoid NULL pointer dereference To: Ethan Zhao , bhelgaas@google.com, oohall@gmail.com, ruscur@russell.cc, lukas@wunner.de, andriy.shevchenko@linux.intel.com, stuart.w.hayes@gmail.com, mr.nuke.me@gmail.com, mika.westerberg@linux.intel.com Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, ashok.raj@linux.intel.com, xerces.zhao@gmail.com References: <20201007113158.48933-1-haifeng.zhao@intel.com> <20201007113158.48933-2-haifeng.zhao@intel.com> From: "Kuppuswamy, Sathyanarayanan" Message-ID: <0430ee93-2561-84fc-3eba-3c66374b6cd8@intel.com> Date: Wed, 7 Oct 2020 10:24:39 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20201007113158.48933-2-haifeng.zhao@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On 10/7/20 4:31 AM, Ethan Zhao wrote: > During DPC error injection test we found there is race condition between > pciehp and DPC driver, NULL pointer dereference caused panic as following > > # setpci -s 64:02.0 0x196.w=000a > // 64:02.0 is rootport has DPC capability > # setpci -s 65:00.0 0x04.w=0544 > // 65:00.0 is NVMe SSD populated in above port > # mount /dev/nvme0n1p1 nvme > > (tested on stable 5.8 & ICS(Ice Lake SP platform, see > https://en.wikichip.org/wiki/intel/microarchitectures/ice_lake_(server)) > > BUG: kernel NULL pointer dereference, address: 0000000000000050 > ... > CPU: 12 PID: 513 Comm: irq/124-pcie-dp Not tainted 5.8.0-0.0.7.el8.x86_64+ #1 > RIP: 0010:report_error_detected.cold.4+0x7d/0xe6 > Code: b6 d0 e8 e8 fe 11 00 e8 16 c5 fb ff be 06 00 00 00 48 89 df e8 d3 65 ff > ff b8 06 00 00 00 e9 75 fc ff ff 48 8b 43 68 45 31 c9 <48> 8b 50 50 48 83 3a 00 > 41 0f 94 c1 45 31 c0 48 85 d2 41 0f 94 c0 > RSP: 0018:ff8e06cf8762fda8 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ff4e3eaacf42a000 RCX: ff4e3eb31f223c01 > RDX: ff4e3eaacf42a140 RSI: ff4e3eb31f223c00 RDI: ff4e3eaacf42a138 > RBP: ff8e06cf8762fdd0 R08: 00000000000000bf R09: 0000000000000000 > R10: 000000eb8ebeab53 R11: ffffffff93453258 R12: 0000000000000002 > R13: ff4e3eaacf42a130 R14: ff8e06cf8762fe2c R15: ff4e3eab44733828 > FS: 0000000000000000(0000) GS:ff4e3eab1fd00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000050 CR3: 0000000f8f80a004 CR4: 0000000000761ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > PKRU: 55555554 > Call Trace: > ? report_normal_detected+0x20/0x20 > report_frozen_detected+0x16/0x20 > pci_walk_bus+0x75/0x90 > ? dpc_irq+0x90/0x90 > pcie_do_recovery+0x157/0x201 > ? irq_finalize_oneshot.part.47+0xe0/0xe0 > dpc_handler+0x29/0x40 > irq_thread_fn+0x24/0x60 > ... > > Debug shows when port DPC feature was enabled and triggered by errors, > DLLSC/PDC/DPC interrupts will be sent to pciehp and DPC driver almost > at the same time, and no delay between them is required by specification. > so DPC driver and pciehp drivers may handle these interrupts cocurrently. > > While DPC driver is doing pci_walk_bus() and calling device driver's > callback without pci_dev_get() to increase device reference count, the > device and its driver instance are likely being freed by > pci_stop_and_removed_bus_device() > -> pci_dev_put(). > > So does pci_dev_get() before using the device instance to avoid NULL > pointer dereference. Won't it be better if you get this in pcie_do_recovery()? > > Signed-off-by: Ethan Zhao > Tested-by: Wen Jin > Tested-by: Shanshan Zhang > --- > Changes: > v2: revise doc according to Andy's suggestion. > v3: no change. > v4: no change. > v5: no change. > v6: moved to [1/5] from [3/5] and revised comment according to Lukas' > suggestion. > v7: no change. > v8: no change. > > drivers/pci/pcie/err.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/drivers/pci/pcie/err.c b/drivers/pci/pcie/err.c > index c543f419d8f9..e35c4480c86b 100644 > --- a/drivers/pci/pcie/err.c > +++ b/drivers/pci/pcie/err.c > @@ -52,6 +52,8 @@ static int report_error_detected(struct pci_dev *dev, > pci_ers_result_t vote; > const struct pci_error_handlers *err_handler; > > + if (!pci_dev_get(dev)) > + return 0; > device_lock(&dev->dev); > if (!pci_dev_set_io_state(dev, state) || > !dev->driver || > @@ -76,6 +78,7 @@ static int report_error_detected(struct pci_dev *dev, > pci_uevent_ers(dev, vote); > *result = merge_result(*result, vote); > device_unlock(&dev->dev); > + pci_dev_put(dev); > return 0; > } > > @@ -94,6 +97,8 @@ static int report_mmio_enabled(struct pci_dev *dev, void *data) > pci_ers_result_t vote, *result = data; > const struct pci_error_handlers *err_handler; > > + if (!pci_dev_get(dev)) > + return 0; > device_lock(&dev->dev); > if (!dev->driver || > !dev->driver->err_handler || > @@ -105,6 +110,7 @@ static int report_mmio_enabled(struct pci_dev *dev, void *data) > *result = merge_result(*result, vote); > out: > device_unlock(&dev->dev); > + pci_dev_put(dev); > return 0; > } > > @@ -113,6 +119,8 @@ static int report_slot_reset(struct pci_dev *dev, void *data) > pci_ers_result_t vote, *result = data; > const struct pci_error_handlers *err_handler; > > + if (!pci_dev_get(dev)) > + return 0; > device_lock(&dev->dev); > if (!dev->driver || > !dev->driver->err_handler || > @@ -124,6 +132,7 @@ static int report_slot_reset(struct pci_dev *dev, void *data) > *result = merge_result(*result, vote); > out: > device_unlock(&dev->dev); > + pci_dev_put(dev); > return 0; > } > > @@ -131,6 +140,8 @@ static int report_resume(struct pci_dev *dev, void *data) > { > const struct pci_error_handlers *err_handler; > > + if (!pci_dev_get(dev)) > + return 0; > device_lock(&dev->dev); > if (!pci_dev_set_io_state(dev, pci_channel_io_normal) || > !dev->driver || > @@ -143,6 +154,7 @@ static int report_resume(struct pci_dev *dev, void *data) > out: > pci_uevent_ers(dev, PCI_ERS_RESULT_RECOVERED); > device_unlock(&dev->dev); > + pci_dev_put(dev); > return 0; > } > -- Sathyanarayanan Kuppuswamy Linux Kernel Developer