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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=no 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 4DECFC2BBE2 for ; Sun, 8 Dec 2019 13:55:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2B349206F4 for ; Sun, 8 Dec 2019 13:55:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727170AbfLHNz3 (ORCPT ); Sun, 8 Dec 2019 08:55:29 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:60544 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726917AbfLHNyq (ORCPT ); Sun, 8 Dec 2019 08:54:46 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1idx1H-0007ia-Kn; Sun, 08 Dec 2019 13:54:43 +0000 Received: from ben by deadeye with local (Exim 4.93-RC1) (envelope-from ) id 1idx1F-0002Q3-QE; Sun, 08 Dec 2019 13:54:41 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "Johan Hovold" , syzbot+0761012cebf7bdb38137@syzkaller.appspotmail.com, "Greg Kroah-Hartman" Date: Sun, 08 Dec 2019 13:53:53 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 69/72] USB: iowarrior: fix use-after-free on disconnect In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.79-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Johan Hovold commit edc4746f253d907d048de680a621e121517f484b upstream. A recent fix addressing a deadlock on disconnect introduced a new bug by moving the present flag out of the critical section protected by the driver-data mutex. This could lead to a racing release() freeing the driver data before disconnect() is done with it. Due to insufficient locking a related use-after-free could be triggered also before the above mentioned commit. Specifically, the driver needs to hold the driver-data mutex also while checking the opened flag at disconnect(). Fixes: c468a8aa790e ("usb: iowarrior: fix deadlock on disconnect") Fixes: 946b960d13c1 ("USB: add driver for iowarrior devices.") Reported-by: syzbot+0761012cebf7bdb38137@syzkaller.appspotmail.com Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20191009104846.5925-2-johan@kernel.org Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/misc/iowarrior.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/drivers/usb/misc/iowarrior.c +++ b/drivers/usb/misc/iowarrior.c @@ -898,8 +898,6 @@ static void iowarrior_disconnect(struct dev = usb_get_intfdata(interface); mutex_lock(&iowarrior_open_disc_lock); usb_set_intfdata(interface, NULL); - /* prevent device read, write and ioctl */ - dev->present = 0; minor = dev->minor; mutex_unlock(&iowarrior_open_disc_lock); @@ -910,8 +908,7 @@ static void iowarrior_disconnect(struct mutex_lock(&dev->mutex); /* prevent device read, write and ioctl */ - - mutex_unlock(&dev->mutex); + dev->present = 0; if (dev->opened) { /* There is a process that holds a filedescriptor to the device , @@ -921,8 +918,10 @@ static void iowarrior_disconnect(struct usb_kill_urb(dev->int_in_urb); wake_up_interruptible(&dev->read_wait); wake_up_interruptible(&dev->write_wait); + mutex_unlock(&dev->mutex); } else { /* no process is using the device, cleanup now */ + mutex_unlock(&dev->mutex); iowarrior_delete(dev); }