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=-15.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 375B6C433ED for ; Fri, 2 Apr 2021 15:06:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0FDE66112F for ; Fri, 2 Apr 2021 15:06:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231160AbhDBPG3 (ORCPT ); Fri, 2 Apr 2021 11:06:29 -0400 Received: from mail.kernel.org ([198.145.29.99]:57734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229553AbhDBPG3 (ORCPT ); Fri, 2 Apr 2021 11:06:29 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3409361103; Fri, 2 Apr 2021 15:06:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617375987; bh=Zz61+Zv+0eQq6UNIJIIuqH0bH3OpUwYDc4oQL8V3jq8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Px4srRQ2HP1H9cR723OYPVptqskOEl4eynqXNC2SML4LPE6/1Oiom0rTq429gBMmc j/De5i4vBBE9pDUO7BRkOT6/ZaNfj+8NtymcedhKh2QOYuYDzV5uELhG03kG6nVQBV JJkxxrAc0hmSRito8+UeHuFMFRtnU73npB+nozgU= Date: Fri, 2 Apr 2021 17:06:25 +0200 From: Greg KH To: Yufen Yu Cc: linux-kernel@vger.kernel.org, rafael@kernel.org, axboe@kernel.dk, hch@lst.de, linux-block@vger.kernel.org Subject: Re: [PATCH] drivers core: don't do anything in device_del() when device_add() fail Message-ID: References: <20210401130138.2164928-1-yuyufen@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210401130138.2164928-1-yuyufen@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Thu, Apr 01, 2021 at 09:01:38AM -0400, Yufen Yu wrote: > Recently, our syzbot test reported NULL pointer dereference in > device_del() by injecting memory allocation fail in device_add(). Don't do that :) > For now, callers of device_add(), such as add_disk(), may ignore > device_add()'s fail and go on working. Please fix up those users, if device_add() fails there is no need to call device_del(). > In unregister path, it will > call device_del() from del_gendisk(). That can cause various NULL > pointer dereference, including dev->p is NULL in kill_device(), > 'name' is NULL in sysfs_remove_link(), kobj->sd is 'NULL' when call > dpm_sysfs_remove(), and so on. > > To avoid these kernel panic, we call device_del() only when device_add() > is success. As Rafael said, that's not what you are doing here, so even if I wanted to take this patch, I can't. > > Signed-off-by: Yufen Yu > --- > drivers/base/core.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index f29839382f81..a10ec5dbc577 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -3380,6 +3380,9 @@ void device_del(struct device *dev) > struct class_interface *class_intf; > unsigned int noio_flag; > > + if (!dev->p) > + return; Also, this isn't a good test as it's not obvious what you are trying to check for here. thanks, greg k-h