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Wed, 15 Nov 2023 19:06:57 -0800 (PST) Message-ID: <6824ece2-33ee-63f4-2c7a-7033556325cb@redhat.com> Date: Thu, 16 Nov 2023 11:06:52 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in To: Wenchao Hao , Ilya Dryomov Cc: Jeff Layton , ceph-devel@vger.kernel.org, linux-kernel@vger.kernel.org, louhongxiang@huawei.com References: <20231114153108.1932884-1-haowenchao2@huawei.com> <5a1766c6-d923-a4e5-c5be-15b953372ef5@redhat.com> <5eb54f3e-3438-ba47-3d43-baf6b27aad0e@huawei.com> Content-Language: en-US From: Xiubo Li In-Reply-To: <5eb54f3e-3438-ba47-3d43-baf6b27aad0e@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/16/23 10:54, Wenchao Hao wrote: > 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? > Yeah, please. Let's fix them all. Thanks - Xiubo > Thanks > >> Thanks >> >> - Xiubo >> >> >>> Thanks, >>> >>>                  Ilya >>> >> >