2023-11-15 12:33:25

by Ilya Dryomov

[permalink] [raw]
Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in

On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li <[email protected]> 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 <[email protected]>
> > ---
> > 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 <[email protected]>
>
> 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.

Am I missing something that makes this qualify for stable?

Thanks,

Ilya


2023-11-15 13:17:52

by Xiubo Li

[permalink] [raw]
Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in


On 11/15/23 20:32, Ilya Dryomov wrote:
> On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li <[email protected]> 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 <[email protected]>
>>> ---
>>> 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 <[email protected]>
>>
>> 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.

If that's not worth to make it for stable, let's remove it.

Thanks

- Xiubo

>
> Thanks,
>
> Ilya
>

2023-11-15 13:26:21

by Ilya Dryomov

[permalink] [raw]
Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in

On Wed, Nov 15, 2023 at 2:17 PM Xiubo Li <[email protected]> wrote:
>
>
> On 11/15/23 20:32, Ilya Dryomov wrote:
> > On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li <[email protected]> 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 <[email protected]>
> >>> ---
> >>> 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 <[email protected]>
> >>
> >> 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.

Thanks,

Ilya

2023-11-15 13:35:20

by Xiubo Li

[permalink] [raw]
Subject: Re: [PATCH] ceph: quota: Fix invalid pointer access in


On 11/15/23 21:25, Ilya Dryomov wrote:
> On Wed, Nov 15, 2023 at 2:17 PM Xiubo Li <[email protected]> wrote:
>>
>> On 11/15/23 20:32, Ilya Dryomov wrote:
>>> On Wed, Nov 15, 2023 at 1:35 AM Xiubo Li <[email protected]> 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 <[email protected]>
>>>>> ---
>>>>> 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 <[email protected]>
>>>>
>>>> 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 ?

Thanks

- Xiubo


> Thanks,
>
> Ilya
>