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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E1AB5ECAAD4 for ; Tue, 30 Aug 2022 12:54:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230302AbiH3Myh (ORCPT ); Tue, 30 Aug 2022 08:54:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229636AbiH3Mx6 (ORCPT ); Tue, 30 Aug 2022 08:53:58 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 13D51132845; Tue, 30 Aug 2022 05:53:49 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6725C616B5; Tue, 30 Aug 2022 12:53:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6550FC433D7; Tue, 30 Aug 2022 12:53:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1661864027; bh=qQ+Ls2PqvI0VuxPbDMq27sZY6OGPoQuUGYChfjWAHP4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=YHaEIXCZ3BglGoarg69NTxqto+v+mvRSqBAdukUaNJUx/ioYDQtQGBPZoa6lSYhuS RpD7W76zc2HIhflJJx5Sg6zYZzOlfIQphHsHKS3oHGprtbS0ma/Ezw07Ozh9/iGFz7 ooE1EJUAQW6bu37/SmkG/VsTSk8BeH5LqKps+mJI= Date: Tue, 30 Aug 2022 14:53:44 +0200 From: Greg Kroah-Hartman To: Linyu Yuan Cc: Heikki Krogerus , Takashi Iwai , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [REGRESSION 5.19] NULL dereference by ucsi_acpi driver Message-ID: References: <87r11cmbx0.wl-tiwai@suse.de> <09f1204c-1256-e737-b769-be899870c946@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 30, 2022 at 02:51:54PM +0200, Greg Kroah-Hartman wrote: > On Mon, Aug 22, 2022 at 10:44:26AM +0800, Linyu Yuan wrote: > > > > On 8/21/2022 2:40 AM, Greg Kroah-Hartman wrote: > > > On Fri, Aug 19, 2022 at 06:32:43PM +0200, Takashi Iwai wrote: > > > > Hi, > > > > > > > > we've got multiple reports about 5.19 kernel starting crashing after > > > > some time, and this turned out to be triggered by ucsi_acpi driver. > > > > The details are found in: > > > > https://bugzilla.suse.com/show_bug.cgi?id=1202386 > > > > > > > > The culprit seems to be the commit 87d0e2f41b8c > > > > usb: typec: ucsi: add a common function ucsi_unregister_connectors() > > > Adding Heikki to the thread... > > > > > > > This commit looks as if it were a harmless cleanup, but this failed in > > > > a subtle way. Namely, in the error scenario, the driver gets an error > > > > at ucsi_register_altmodes(), and goes to the error handling to release > > > > the resources. Through this refactoring, the release part was unified > > > > to a funciton ucsi_unregister_connectors(). And there, it has a NULL > > > > check of con->wq, and it bails out the loop if it's NULL. > > > > Meanwhile, ucsi_register_port() itself still calls destroy_workqueue() > > > > and clear con->wq at its error path. This ended up in the leftover > > > > power supply device with the uninitialized / cleared device. > > > > > > > > It was confirmed that the problem could be avoided by a simple > > > > revert. > > > I'll be glad to revert this now, unless Heikki thinks: > > > > > > > I guess another fix could be removing the part clearing con->wq, i.e. > > > > > > > > --- a/drivers/usb/typec/ucsi/ucsi.c > > > > +++ b/drivers/usb/typec/ucsi/ucsi.c > > > > @@ -1192,11 +1192,6 @@ static int ucsi_register_port(struct ucsi *ucsi, int index) > > > > out_unlock: > > > > mutex_unlock(&con->lock); > > > > - if (ret && con->wq) { > > > > - destroy_workqueue(con->wq); > > > > - con->wq = NULL; > > > > - } > > > > - > > > > return ret; > > > > } > > > > > > > > ... but it's totally untested and I'm not entirely sure whether it's > > > > better. > > > > this part is original code, yes, but when I make the change you mentioned, > > > > as in the function ucsi_unregister_connectors(),  just use con->wq to > > represent which connector initialized previous, > > > > indeed if we clear it in ucsi_register_port(), something will left unclear. > > > > please send a patch to fix it. > > > > I think your change is good. > > Ok, can someone send me a patch to apply to the tree for this? Oh nevermind, I already have the revert in my tree, sorry for the noise. greg k-h