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 16144C2BB3F for ; Thu, 16 Nov 2023 02:54:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344548AbjKPCyj (ORCPT ); Wed, 15 Nov 2023 21:54:39 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59686 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230259AbjKPCyi (ORCPT ); Wed, 15 Nov 2023 21:54:38 -0500 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EA2CB197; Wed, 15 Nov 2023 18:54:33 -0800 (PST) Received: from kwepemm000012.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4SW4PL0XcczvQjR; Thu, 16 Nov 2023 10:54:14 +0800 (CST) Received: from [10.174.178.220] (10.174.178.220) by kwepemm000012.china.huawei.com (7.193.23.142) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 16 Nov 2023 10:54:30 +0800 Message-ID: <5eb54f3e-3438-ba47-3d43-baf6b27aad0e@huawei.com> Date: Thu, 16 Nov 2023 10:54:29 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in To: Xiubo Li , Ilya Dryomov CC: Jeff Layton , , , References: <20231114153108.1932884-1-haowenchao2@huawei.com> <5a1766c6-d923-a4e5-c5be-15b953372ef5@redhat.com> Content-Language: en-US From: Wenchao Hao In-Reply-To: <5a1766c6-d923-a4e5-c5be-15b953372ef5@redhat.com> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.178.220] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm000012.china.huawei.com (7.193.23.142) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/11/15 21:34, Xiubo Li wrote: > > On 11/15/23 21:25, Ilya Dryomov wrote: >> On Wed, Nov 15, 2023 at 2:17 PM Xiubo Li wrote: >>> >>> On 11/15/23 20:32, Ilya Dryomov wrote: >>>> On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li wrote: >>>>> On 11/14/23 23:31, Wenchao Hao wrote: >>>>>> This issue is reported by smatch, get_quota_realm() might return >>>>>> ERR_PTR, so we should using IS_ERR_OR_NULL here to check the return >>>>>> value. >>>>>> >>>>>> Signed-off-by: Wenchao Hao >>>>>> --- >>>>>>     fs/ceph/quota.c | 2 +- >>>>>>     1 file changed, 1 insertion(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/fs/ceph/quota.c b/fs/ceph/quota.c >>>>>> index 9d36c3532de1..c4b2929c6a83 100644 >>>>>> --- a/fs/ceph/quota.c >>>>>> +++ b/fs/ceph/quota.c >>>>>> @@ -495,7 +495,7 @@ bool ceph_quota_update_statfs(struct ceph_fs_client *fsc, struct kstatfs *buf) >>>>>>         realm = get_quota_realm(mdsc, d_inode(fsc->sb->s_root), >>>>>>                                 QUOTA_GET_MAX_BYTES, true); >>>>>>         up_read(&mdsc->snap_rwsem); >>>>>> -     if (!realm) >>>>>> +     if (IS_ERR_OR_NULL(realm)) >>>>>>                 return false; >>>>>> >>>>>>         spin_lock(&realm->inodes_with_caps_lock); >>>>> Good catch. >>>>> >>>>> Reviewed-by: Xiubo Li >>>>> >>>>> We should CC the stable mail list. >>>> Hi Xiubo, >>>> >>>> What exactly is being fixed here?  get_quota_realm() is called with >>>> retry=true, which means that no errors can be returned -- EAGAIN, the >>>> only error that get_quota_realm() can otherwise generate, would be >>>> handled internally by retrying. >>> Yeah, that's true. >>> >>>> Am I missing something that makes this qualify for stable? >>> Actually it's just for the smatch check for now. >>> >>> IMO we shouldn't depend on the 'retry', just potentially for new changes >>> in future could return a ERR_PTR and cause potential bugs. >> At present, ceph_quota_is_same_realm() also depends on it -- note how >> old_realm isn't checked for errors at all and new_realm is only checked >> for EAGAIN there. >> >>> If that's not worth to make it for stable, let's remove it. >> Yes, let's remove it.  Please update the commit message as well, so >> that it's clear that this is squashing a static checker warning and >> doesn't actually fix any immediate bug. > > WenChao, > > Could update the commit comment and send the V2 ? > OK, I would update the commit comment as following: This issue is reported by smatch, get_quota_realm() might return ERR_PTR. It's not a immediate bug because get_quota_realm() is called with 'retry=true', no errors can be returned. While we still should check the return value of get_quota_realm() with IS_ERR_OR_NULL to avoid potential bugs if get_quota_realm() is changed to return other ERR_PTR in future. What's more, should I change the ceph_quota_is_same_realm() too? Thanks > Thanks > > - Xiubo > > >> Thanks, >> >>                  Ilya >> >