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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 CF7E0C47095 for ; Wed, 9 Jun 2021 09:42:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B84C0613AC for ; Wed, 9 Jun 2021 09:42:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238159AbhFIJov (ORCPT ); Wed, 9 Jun 2021 05:44:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:36666 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238162AbhFIJou (ORCPT ); Wed, 9 Jun 2021 05:44:50 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0143E6136D; Wed, 9 Jun 2021 09:42:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623231775; bh=MJZ1xoC4SXgXBo4T0p99ORsxRs0/VJPIQky2Q1NkXRw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=lAMnwkE82U1Ge6HXVNIWaT9Ism9kuGK/rhlV3hXhQoUhjwYgKnfVO6hOn5rW15d18 Ycfm5PWJ0U3Ys8zsrPQNtJDmtj15kvVGkA6lJ56JKw3C5LQJt5vKLcfIlKaPKNLZCw f1YUPVNs3vQ6oB+ZixScG4O69Ednv6JDL29cLhEI= Date: Wed, 9 Jun 2021 11:42:53 +0200 From: Greg Kroah-Hartman To: Jack Pham Cc: Peter Chen , balbi@kernel.org, linux-usb@vger.kernel.org Subject: Re: [PATCH 1/1] usb: dwc3: core: fix kernel panic when do reboot Message-ID: References: <20210608105656.10795-1-peter.chen@kernel.org> <20210608164933.GA2601@jackp-linux.qualcomm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Wed, Jun 09, 2021 at 11:01:07AM +0200, Greg Kroah-Hartman wrote: > On Tue, Jun 08, 2021 at 09:50:01AM -0700, Jack Pham wrote: > > Hi Peter, > > > > On Tue, Jun 08, 2021 at 06:56:56PM +0800, Peter Chen wrote: > > > When do system reboot, it calls dwc3_shutdown and the whole debugfs > > > for dwc3 has removed first, when the gadget tries to do deinit, and > > > remove debugfs for its endpoints, it meets NULL pointer dereference > > > issue when call debugfs_lookup. Fix it by removing the whole dwc3 > > > debugfs later than dwc3_drd_exit. > > > > Ouch, thanks for catching this! I think in your previous reply[1] you > > did warn about the debugfs_remove_recursive() getting called twice, but > > it seems here the issue is due to the debugfs_lookup() getting called on > > a stale dwc->root pointer after it was already removed. > > We can also fix this by getting rid of that "root" pointer as it's > useless (we can look it up if we need it.) I'll send a patch later to > do that, as it's a good idea to do anyway, and is independant of this > fix. Now sent: https://lore.kernel.org/r/20210609093924.3293230-1-gregkh@linuxfoundation.org