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 3AD06C47095 for ; Wed, 9 Jun 2021 09:01:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 257DD61183 for ; Wed, 9 Jun 2021 09:01:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233930AbhFIJDX (ORCPT ); Wed, 9 Jun 2021 05:03:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:49644 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231919AbhFIJDV (ORCPT ); Wed, 9 Jun 2021 05:03:21 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id C925A61182; Wed, 9 Jun 2021 09:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1623229270; bh=QY9p7QigWQvKh0dZh2qPkN32nYvRy2rehUvJ5ev1hT4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=JVIWJpu0fo5rKal/RoOce324EqW8gZNwfqhaF/V1jTUN/6MbjMIJI5DBV2s6U+PfS vk8n4SxbZzaPUH9uF22fEIuPb5OS0/zuc15Jg5oHaTNtZQdEM08enZREIS8zX7IF/k 9U+alHBTR4avIiwgvTfLKZ8rO6riEW6SdFWriXHM= Date: Wed, 9 Jun 2021 11:01:07 +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: <20210608164933.GA2601@jackp-linux.qualcomm.com> Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org 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. thanks, greg k-h