From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752704AbdJCMW2 (ORCPT ); Tue, 3 Oct 2017 08:22:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60072 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751987AbdJCMW0 (ORCPT ); Tue, 3 Oct 2017 08:22:26 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nicolai Stange , Bjorn Helgaas Subject: [PATCH 4.4 26/41] PCI: Fix race condition with driver_override Date: Tue, 3 Oct 2017 14:21:27 +0200 Message-Id: <20171003114221.518347361@linuxfoundation.org> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20171003114219.900672076@linuxfoundation.org> References: <20171003114219.900672076@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicolai Stange commit 9561475db680f7144d2223a409dd3d7e322aca03 upstream. The driver_override implementation is susceptible to a race condition when different threads are reading vs. storing a different driver override. Add locking to avoid the race condition. This is in close analogy to commit 6265539776a0 ("driver core: platform: fix race condition with driver_override") from Adrian Salido. Fixes: 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override") Signed-off-by: Nicolai Stange Signed-off-by: Bjorn Helgaas Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pci-sysfs.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -522,7 +522,7 @@ static ssize_t driver_override_store(str const char *buf, size_t count) { struct pci_dev *pdev = to_pci_dev(dev); - char *driver_override, *old = pdev->driver_override, *cp; + char *driver_override, *old, *cp; /* We need to keep extra room for a newline */ if (count >= (PAGE_SIZE - 1)) @@ -536,12 +536,15 @@ static ssize_t driver_override_store(str if (cp) *cp = '\0'; + device_lock(dev); + old = pdev->driver_override; if (strlen(driver_override)) { pdev->driver_override = driver_override; } else { kfree(driver_override); pdev->driver_override = NULL; } + device_unlock(dev); kfree(old); @@ -552,8 +555,12 @@ static ssize_t driver_override_show(stru struct device_attribute *attr, char *buf) { struct pci_dev *pdev = to_pci_dev(dev); + ssize_t len; - return snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override); + device_lock(dev); + len = snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override); + device_unlock(dev); + return len; } static DEVICE_ATTR_RW(driver_override);