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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 8564EC433E7 for ; Wed, 2 Sep 2020 15:13:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DD8820773 for ; Wed, 2 Sep 2020 15:13:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727780AbgIBPNw (ORCPT ); Wed, 2 Sep 2020 11:13:52 -0400 Received: from netrider.rowland.org ([192.131.102.5]:42217 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1727961AbgIBPMk (ORCPT ); Wed, 2 Sep 2020 11:12:40 -0400 Received: (qmail 626110 invoked by uid 1000); 2 Sep 2020 11:12:33 -0400 Date: Wed, 2 Sep 2020 11:12:33 -0400 From: Alan Stern To: Pavel Machek Cc: Greg Kroah-Hartman , linux-kernel@vger.kernel.org, stable@vger.kernel.org, syzbot+c2c3302f9c601a4b1be2@syzkaller.appspotmail.com Subject: Re: [PATCH 4.19 108/125] USB: yurex: Fix bad gfp argument Message-ID: <20200902151233.GC624583@rowland.harvard.edu> References: <20200901150934.576210879@linuxfoundation.org> <20200901150939.905188730@linuxfoundation.org> <20200902125827.GA8817@duo.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200902125827.GA8817@duo.ucw.cz> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 02, 2020 at 02:58:27PM +0200, Pavel Machek wrote: > Hi! > > > The syzbot fuzzer identified a bug in the yurex driver: It passes > > GFP_KERNEL as a memory-allocation flag to usb_submit_urb() at a time > > when its state is TASK_INTERRUPTIBLE, not TASK_RUNNING: > > Yeah, and instead of fixing the bug, patch papers over it, reducing > reliability of the driver in the process. > > > This patch changes the call to use GFP_ATOMIC instead of GFP_KERNEL. > > Fixing it properly should be as simple as moving prepare_to_wait down, > no? Sigh. That never occurred to me, but of course it is right. Acked-by: Alan Stern Alan Stern > Signed-off-by: Pavel Machek (CIP) > > diff --git a/drivers/usb/misc/yurex.c b/drivers/usb/misc/yurex.c > index 785080f79073..5fbbb57e6e95 100644 > --- a/drivers/usb/misc/yurex.c > +++ b/drivers/usb/misc/yurex.c > @@ -489,10 +489,10 @@ static ssize_t yurex_write(struct file *file, const char __user *user_buffer, > } > > /* send the data as the control msg */ > - prepare_to_wait(&dev->waitq, &wait, TASK_INTERRUPTIBLE); > dev_dbg(&dev->interface->dev, "%s - submit %c\n", __func__, > dev->cntl_buffer[0]); > - retval = usb_submit_urb(dev->cntl_urb, GFP_ATOMIC); > + retval = usb_submit_urb(dev->cntl_urb, GFP_KERNEL); > + prepare_to_wait(&dev->waitq, &wait, TASK_INTERRUPTIBLE); > if (retval >= 0) > timeout = schedule_timeout(YUREX_WRITE_TIMEOUT); > finish_wait(&dev->waitq, &wait); > > > Best regards, > Pavel > > -- > (english) http://www.livejournal.com/~pavelmachek > (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html