From patchwork Tue Feb 2 01:47:53 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dan Williams X-Patchwork-Id: 12060357 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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,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 D7CCDC433E0 for ; Tue, 2 Feb 2021 01:47:58 +0000 (UTC) Received: from ml01.01.org (ml01.01.org [198.145.21.10]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7CBF164EBD for ; Tue, 2 Feb 2021 01:47:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7CBF164EBD Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-nvdimm-bounces@lists.01.org Received: from ml01.vlan13.01.org (localhost [IPv6:::1]) by ml01.01.org (Postfix) with ESMTP id 2100F100EA920; Mon, 1 Feb 2021 17:47:58 -0800 (PST) Received-SPF: Pass (mailfrom) identity=mailfrom; client-ip=192.55.52.43; helo=mga05.intel.com; envelope-from=dan.j.williams@intel.com; receiver= Received: from mga05.intel.com (mga05.intel.com [192.55.52.43]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ml01.01.org (Postfix) with ESMTPS id B7F73100EB352 for ; Mon, 1 Feb 2021 17:47:55 -0800 (PST) IronPort-SDR: 49/7GyPxvgD+SNPrgrv4gtEUxIGiRLvTibGJxXBMIXxuzsOYNMU4CrTN5O1jlo+K/6e6ieVFCq QgnQsxbOsSDw== X-IronPort-AV: E=McAfee;i="6000,8403,9882"; a="265613943" X-IronPort-AV: E=Sophos;i="5.79,393,1602572400"; d="scan'208";a="265613943" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Feb 2021 17:47:54 -0800 IronPort-SDR: cTIokm0jo98k7fEoro2xwG68uHTxSwmfepHt18u5dRUaS9fvSx+3D9uzaJNOX54DyuGEmnknEG rN+5ldPYUG8Q== X-IronPort-AV: E=Sophos;i="5.79,393,1602572400"; d="scan'208";a="370192789" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.25]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 01 Feb 2021 17:47:54 -0800 Subject: [PATCH] libnvdimm/dimm: Avoid race between probe and available_slots_show() From: Dan Williams To: linux-nvdimm@lists.01.org Date: Mon, 01 Feb 2021 17:47:53 -0800 Message-ID: <161223047357.4134109.9331035508023355722.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Message-ID-Hash: BS2CZHHNRYHKNTILAYPEXJKRJ7W6VWNQ X-Message-ID-Hash: BS2CZHHNRYHKNTILAYPEXJKRJ7W6VWNQ X-MailFrom: dan.j.williams@intel.com X-Mailman-Rule-Misses: dmarc-mitigation; no-senders; approved; emergency; loop; banned-address; member-moderation; nonmember-moderation; administrivia; implicit-dest; max-recipients; max-size; news-moderation; no-subject; suspicious-header CC: stable@vger.kernel.org, Coly Li , Richard Palethorpe , linux-kernel@vger.kernel.org X-Mailman-Version: 3.1.1 Precedence: list List-Id: "Linux-nvdimm developer list." Archived-At: List-Archive: List-Help: List-Post: List-Subscribe: List-Unsubscribe: Richard reports that the following test: (while true; do cat /sys/bus/nd/devices/nmem*/available_slots 2>&1 > /dev/null done) & while true; do for i in $(seq 0 4); do echo nmem$i > /sys/bus/nd/drivers/nvdimm/bind done for i in $(seq 0 4); do echo nmem$i > /sys/bus/nd/drivers/nvdimm/unbind done done ...fails with a crash signature like: divide error: 0000 [#1] SMP KASAN PTI RIP: 0010:nd_label_nfree+0x134/0x1a0 [libnvdimm] [..] Call Trace: available_slots_show+0x4e/0x120 [libnvdimm] dev_attr_show+0x42/0x80 ? memset+0x20/0x40 sysfs_kf_seq_show+0x218/0x410 The root cause is that available_slots_show() consults driver-data, but fails to synchronize against device-unbind setting up a TOCTOU race to access uninitialized memory. Validate driver-data under the device-lock. Fixes: 4d88a97aa9e8 ("libnvdimm, nvdimm: dimm driver and base libnvdimm device-driver infrastructure") Cc: Cc: Vishal Verma Cc: Dave Jiang Cc: Ira Weiny Cc: Coly Li Reported-by: Richard Palethorpe Signed-off-by: Dan Williams --- drivers/nvdimm/dimm_devs.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c index b59032e0859b..9d208570d059 100644 --- a/drivers/nvdimm/dimm_devs.c +++ b/drivers/nvdimm/dimm_devs.c @@ -335,16 +335,16 @@ static ssize_t state_show(struct device *dev, struct device_attribute *attr, } static DEVICE_ATTR_RO(state); -static ssize_t available_slots_show(struct device *dev, - struct device_attribute *attr, char *buf) +static ssize_t __available_slots_show(struct nvdimm_drvdata *ndd, char *buf) { - struct nvdimm_drvdata *ndd = dev_get_drvdata(dev); + struct device *dev; ssize_t rc; u32 nfree; if (!ndd) return -ENXIO; + dev = ndd->dev; nvdimm_bus_lock(dev); nfree = nd_label_nfree(ndd); if (nfree - 1 > nfree) { @@ -356,6 +356,18 @@ static ssize_t available_slots_show(struct device *dev, nvdimm_bus_unlock(dev); return rc; } + +static ssize_t available_slots_show(struct device *dev, + struct device_attribute *attr, char *buf) +{ + ssize_t rc; + + nd_device_lock(dev); + rc = __available_slots_show(dev_get_drvdata(dev), buf); + nd_device_unlock(dev); + + return rc; +} static DEVICE_ATTR_RO(available_slots); __weak ssize_t security_show(struct device *dev,