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=-3.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 286B4C4321D for ; Thu, 16 Aug 2018 07:40:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E709C214C5 for ; Thu, 16 Aug 2018 07:40:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E709C214C5 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389438AbeHPKgu (ORCPT ); Thu, 16 Aug 2018 06:36:50 -0400 Received: from mail.bootlin.com ([62.4.15.54]:50036 "EHLO mail.bootlin.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727160AbeHPKgu (ORCPT ); Thu, 16 Aug 2018 06:36:50 -0400 Received: by mail.bootlin.com (Postfix, from userid 110) id 56CF320712; Thu, 16 Aug 2018 09:40:13 +0200 (CEST) Received: from localhost (unknown [78.250.249.73]) by mail.bootlin.com (Postfix) with ESMTPSA id 516CA20712; Thu, 16 Aug 2018 09:39:59 +0200 (CEST) From: Alexandre Belloni To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, Alexandre Belloni Subject: [PATCH v2] uio: ensure class is registered before devices Date: Thu, 16 Aug 2018 09:39:41 +0200 Message-Id: <20180816073941.13618-1-alexandre.belloni@bootlin.com> X-Mailer: git-send-email 2.18.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When both uio and the uio drivers are built in the kernel, it is possible for a driver to register devices before the uio class is registered. This may result in a NULL pointer dereference later on in get_device_parent() when accessing the class glue_dirs spinlock. The trace looks like that: Unable to handle kernel NULL pointer dereference at virtual address 00000140 [...] [] _raw_spin_lock+0x14/0x48 [] device_add+0x154/0x6a0 [] device_create_groups_vargs+0x120/0x128 [] device_create+0x54/0x60 [] __uio_register_device+0x120/0x4a8 [] jaguar2_pci_probe+0x2d4/0x558 [] local_pci_probe+0x3c/0xb8 [] pci_device_probe+0x11c/0x180 [] driver_probe_device+0x22c/0x2d8 [] __driver_attach+0xbc/0xc0 [] bus_for_each_dev+0x4c/0x98 [] driver_attach+0x20/0x28 [] bus_add_driver+0x1b8/0x228 [] driver_register+0x60/0xf8 [] __pci_register_driver+0x40/0x48 Return EPROBE_DEFER in that case so the driver can register the device later. Signed-off-by: Alexandre Belloni --- drivers/uio/uio.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c index 5d421d7e8904..55b523f7499b 100644 --- a/drivers/uio/uio.c +++ b/drivers/uio/uio.c @@ -275,6 +275,8 @@ static struct class uio_class = { .dev_groups = uio_groups, }; +bool uio_class_registered; + /* * device functions */ @@ -884,6 +886,9 @@ static int init_uio_class(void) printk(KERN_ERR "class_register failed for uio\n"); goto err_class_register; } + + uio_class_registered = true; + return 0; err_class_register: @@ -894,6 +899,7 @@ static int init_uio_class(void) static void release_uio_class(void) { + uio_class_registered = false; class_unregister(&uio_class); uio_major_cleanup(); } @@ -920,6 +926,9 @@ int __uio_register_device(struct module *owner, struct uio_device *idev; int ret = 0; + if (!uio_class_registered) + return -EPROBE_DEFER; + if (!parent || !info || !info->name || !info->version) return -EINVAL; -- 2.18.0