From patchwork Thu Mar 4 15:24:44 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tetsuo Handa X-Patchwork-Id: 394128 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=-16.8 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, 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 A53CBC43603 for ; Thu, 4 Mar 2021 15:27:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 873F264F9F for ; Thu, 4 Mar 2021 15:27:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234794AbhCDP0q (ORCPT ); Thu, 4 Mar 2021 10:26:46 -0500 Received: from www262.sakura.ne.jp ([202.181.97.72]:62159 "EHLO www262.sakura.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234323AbhCDP0Y (ORCPT ); Thu, 4 Mar 2021 10:26:24 -0500 Received: from fsav302.sakura.ne.jp (fsav302.sakura.ne.jp [153.120.85.133]) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTP id 124FP2gu030903; Fri, 5 Mar 2021 00:25:02 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Received: from www262.sakura.ne.jp (202.181.97.72) by fsav302.sakura.ne.jp (F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp); Fri, 05 Mar 2021 00:25:02 +0900 (JST) X-Virus-Status: clean(F-Secure/fsigk_smtp/550/fsav302.sakura.ne.jp) Received: from localhost.localdomain (M106072142033.v4.enabler.ne.jp [106.72.142.33]) (authenticated bits=0) by www262.sakura.ne.jp (8.15.2/8.15.2) with ESMTPSA id 124FOtn1030882 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 5 Mar 2021 00:25:02 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) From: Tetsuo Handa To: Valentina Manea , Shuah Khan , Greg Kroah-Hartman Cc: Arnd Bergmann , linux-usb@vger.kernel.org, Tetsuo Handa Subject: [PATCH v4 01/12] usb: usbip: introduce usbip_event_mutex for serialization Date: Fri, 5 Mar 2021 00:24:44 +0900 Message-Id: <20210304152455.3685-2-penguin-kernel@I-love.SAKURA.ne.jp> X-Mailer: git-send-email 2.18.4 In-Reply-To: <20210304152455.3685-1-penguin-kernel@I-love.SAKURA.ne.jp> References: <20210304152455.3685-1-penguin-kernel@I-love.SAKURA.ne.jp> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org syzbot is reporting a NULL pointer dereference [1] because usbip modules do not use serialization when attaching/detaching. As a preparation for serializing attach/detach operations, introduce a global mutex, export it via usbip_event_lock_killable()/usbip_event_unlock(), and use it in event_handler(). We don't need to use per a device mutex because event_handler() is processed by a singlethreaded workqueue and ud->tcp_{tx,rx} must not wait for event_handler() to flush. [1] https://syzkaller.appspot.com/bug?extid=95ce4b142579611ef0a9 Reported-by: syzbot Tested-by: syzbot Signed-off-by: Tetsuo Handa --- drivers/usb/usbip/usbip_common.h | 2 ++ drivers/usb/usbip/usbip_event.c | 15 +++++++++++++++ 2 files changed, 17 insertions(+) diff --git a/drivers/usb/usbip/usbip_common.h b/drivers/usb/usbip/usbip_common.h index a7dd6c66aee5..f8e16c75b154 100644 --- a/drivers/usb/usbip/usbip_common.h +++ b/drivers/usb/usbip/usbip_common.h @@ -327,6 +327,8 @@ void usbip_stop_eh(struct usbip_device *ud); void usbip_event_add(struct usbip_device *ud, unsigned long event); int usbip_event_happened(struct usbip_device *ud); int usbip_in_eh(struct task_struct *task); +int usbip_event_lock_killable(void); +void usbip_event_unlock(void); static inline int interface_to_busnum(struct usb_interface *interface) { diff --git a/drivers/usb/usbip/usbip_event.c b/drivers/usb/usbip/usbip_event.c index 5d88917c9631..e05b858f346d 100644 --- a/drivers/usb/usbip/usbip_event.c +++ b/drivers/usb/usbip/usbip_event.c @@ -58,6 +58,19 @@ static struct usbip_device *get_event(void) } static struct task_struct *worker_context; +static DEFINE_MUTEX(usbip_event_mutex); + +int usbip_event_lock_killable(void) +{ + return mutex_lock_killable(&usbip_event_mutex); +} +EXPORT_SYMBOL_GPL(usbip_event_lock_killable); + +void usbip_event_unlock(void) +{ + mutex_unlock(&usbip_event_mutex); +} +EXPORT_SYMBOL_GPL(usbip_event_unlock); static void event_handler(struct work_struct *work) { @@ -68,6 +81,7 @@ static void event_handler(struct work_struct *work) } while ((ud = get_event()) != NULL) { + mutex_lock(&usbip_event_mutex); usbip_dbg_eh("pending event %lx\n", ud->event); /* @@ -91,6 +105,7 @@ static void event_handler(struct work_struct *work) unset_event(ud, USBIP_EH_UNUSABLE); } + mutex_unlock(&usbip_event_mutex); wake_up(&ud->eh_waitq); } }