2023-03-30 18:29:32

by Jeff Layton

Subject: [PATCH] sunrpc: only free unix grouplist after RCU settles

While the unix_gid object is rcu-freed, the group_info list that it
contains is not. Ensure that we only put the group list reference once
we are really freeing the unix_gid object.

Reported-by: Zhi Li <[email protected]>
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2183056
Signed-off-by: Jeff Layton <[email protected]>
---
net/sunrpc/svcauth_unix.c | 17 +++++++++++++----
1 file changed, 13 insertions(+), 4 deletions(-)

diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
index 50e2eb579194..4485088ce27b 100644
--- a/net/sunrpc/svcauth_unix.c
+++ b/net/sunrpc/svcauth_unix.c
@@ -416,14 +416,23 @@ static int unix_gid_hash(kuid_t uid)
return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
}

-static void unix_gid_put(struct kref *kref)
+static void unix_gid_free(struct rcu_head *rcu)
{
- struct cache_head *item = container_of(kref, struct cache_head, ref);
- struct unix_gid *ug = container_of(item, struct unix_gid, h);
+ struct unix_gid *ug = container_of(rcu, struct unix_gid, rcu);
+ struct cache_head *item = &ug->h;
+
if (test_bit(CACHE_VALID, &item->flags) &&
!test_bit(CACHE_NEGATIVE, &item->flags))
put_group_info(ug->gi);
- kfree_rcu(ug, rcu);
+ kfree(ug);
+}
+
+static void unix_gid_put(struct kref *kref)
+{
+ struct cache_head *item = container_of(kref, struct cache_head, ref);
+ struct unix_gid *ug = container_of(item, struct unix_gid, h);
+
+ call_rcu(&ug->rcu, unix_gid_free);
}

static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
--
2.39.2

2023-03-30 18:39:01

by Chuck Lever III

Subject: Re: [PATCH] sunrpc: only free unix grouplist after RCU settles

Hi Jeff-

> On Mar 30, 2023, at 2:24 PM, Jeff Layton <[email protected]> wrote:
>
> While the unix_gid object is rcu-freed, the group_info list that it
> contains is not. Ensure that we only put the group list reference once
> we are really freeing the unix_gid object.
>
> Reported-by: Zhi Li <[email protected]>

Should we also add

Fixes: fd5d2f78261b ("SUNRPC: Make server side AUTH_UNIX use lockless lookups") ?


> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2183056

This bug isn't publicly accessible, fwiw.


> Signed-off-by: Jeff Layton <[email protected]>
> ---
> net/sunrpc/svcauth_unix.c | 17 +++++++++++++----
> 1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
> index 50e2eb579194..4485088ce27b 100644
> --- a/net/sunrpc/svcauth_unix.c
> +++ b/net/sunrpc/svcauth_unix.c
> @@ -416,14 +416,23 @@ static int unix_gid_hash(kuid_t uid)
> return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
> }
>
> -static void unix_gid_put(struct kref *kref)
> +static void unix_gid_free(struct rcu_head *rcu)
> {
> - struct cache_head *item = container_of(kref, struct cache_head, ref);
> - struct unix_gid *ug = container_of(item, struct unix_gid, h);
> + struct unix_gid *ug = container_of(rcu, struct unix_gid, rcu);
> + struct cache_head *item = &ug->h;
> +
> if (test_bit(CACHE_VALID, &item->flags) &&
> !test_bit(CACHE_NEGATIVE, &item->flags))
> put_group_info(ug->gi);
> - kfree_rcu(ug, rcu);
> + kfree(ug);
> +}
> +
> +static void unix_gid_put(struct kref *kref)
> +{
> + struct cache_head *item = container_of(kref, struct cache_head, ref);
> + struct unix_gid *ug = container_of(item, struct unix_gid, h);
> +
> + call_rcu(&ug->rcu, unix_gid_free);
> }
>
> static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
> --
> 2.39.2
>

--
Chuck Lever

2023-03-30 18:56:20

by Jeff Layton

Subject: Re: [PATCH] sunrpc: only free unix grouplist after RCU settles

On Thu, 2023-03-30 at 18:31 +0000, Chuck Lever III wrote:
> Hi Jeff-
>
> > On Mar 30, 2023, at 2:24 PM, Jeff Layton <[email protected]> wrote:
> >
> > While the unix_gid object is rcu-freed, the group_info list that it
> > contains is not. Ensure that we only put the group list reference once
> > we are really freeing the unix_gid object.
> >
> > Reported-by: Zhi Li <[email protected]>
>
> Should we also add
>
> Fixes: fd5d2f78261b ("SUNRPC: Make server side AUTH_UNIX use lockless lookups") ?
>
>

Sure. That does look like when that particular bug crept in.

> > Link: https://bugzilla.redhat.com/show_bug.cgi?id=2183056
>
> This bug isn't publicly accessible, fwiw.
>

Thanks. It should be now.

>
> > Signed-off-by: Jeff Layton <[email protected]>
> > ---
> > net/sunrpc/svcauth_unix.c | 17 +++++++++++++----
> > 1 file changed, 13 insertions(+), 4 deletions(-)
> >
> > diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
> > index 50e2eb579194..4485088ce27b 100644
> > --- a/net/sunrpc/svcauth_unix.c
> > +++ b/net/sunrpc/svcauth_unix.c
> > @@ -416,14 +416,23 @@ static int unix_gid_hash(kuid_t uid)
> > return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
> > }
> >
> > -static void unix_gid_put(struct kref *kref)
> > +static void unix_gid_free(struct rcu_head *rcu)
> > {
> > - struct cache_head *item = container_of(kref, struct cache_head, ref);
> > - struct unix_gid *ug = container_of(item, struct unix_gid, h);
> > + struct unix_gid *ug = container_of(rcu, struct unix_gid, rcu);
> > + struct cache_head *item = &ug->h;
> > +
> > if (test_bit(CACHE_VALID, &item->flags) &&
> > !test_bit(CACHE_NEGATIVE, &item->flags))
> > put_group_info(ug->gi);
> > - kfree_rcu(ug, rcu);
> > + kfree(ug);
> > +}
> > +
> > +static void unix_gid_put(struct kref *kref)
> > +{
> > + struct cache_head *item = container_of(kref, struct cache_head, ref);
> > + struct unix_gid *ug = container_of(item, struct unix_gid, h);
> > +
> > + call_rcu(&ug->rcu, unix_gid_free);
> > }
> >
> > static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
> > --
> > 2.39.2
> >
>
> --
> Chuck Lever
>
>

--
Jeff Layton <[email protected]>

2023-03-30 19:34:49

by Chuck Lever III

Subject: Re: [PATCH] sunrpc: only free unix grouplist after RCU settles

> On Mar 30, 2023, at 2:49 PM, Jeff Layton <[email protected]> wrote:
>
> On Thu, 2023-03-30 at 18:31 +0000, Chuck Lever III wrote:
>> Hi Jeff-
>>
>>> On Mar 30, 2023, at 2:24 PM, Jeff Layton <[email protected]> wrote:
>>>
>>> While the unix_gid object is rcu-freed, the group_info list that it
>>> contains is not. Ensure that we only put the group list reference once
>>> we are really freeing the unix_gid object.
>>>
>>> Reported-by: Zhi Li <[email protected]>
>>
>> Should we also add
>>
>> Fixes: fd5d2f78261b ("SUNRPC: Make server side AUTH_UNIX use lockless lookups") ?
>>
>>
>
> Sure. That does look like when that particular bug crept in.
>
>>> Link: https://bugzilla.redhat.com/show_bug.cgi?id=2183056
>>
>> This bug isn't publicly accessible, fwiw.
>>
>
> Thanks. It should be now.

OK, applied to nfsd-fixes!


>>> Signed-off-by: Jeff Layton <[email protected]>
>>> ---
>>> net/sunrpc/svcauth_unix.c | 17 +++++++++++++----
>>> 1 file changed, 13 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/net/sunrpc/svcauth_unix.c b/net/sunrpc/svcauth_unix.c
>>> index 50e2eb579194..4485088ce27b 100644
>>> --- a/net/sunrpc/svcauth_unix.c
>>> +++ b/net/sunrpc/svcauth_unix.c
>>> @@ -416,14 +416,23 @@ static int unix_gid_hash(kuid_t uid)
>>> return hash_long(from_kuid(&init_user_ns, uid), GID_HASHBITS);
>>> }
>>>
>>> -static void unix_gid_put(struct kref *kref)
>>> +static void unix_gid_free(struct rcu_head *rcu)
>>> {
>>> - struct cache_head *item = container_of(kref, struct cache_head, ref);
>>> - struct unix_gid *ug = container_of(item, struct unix_gid, h);
>>> + struct unix_gid *ug = container_of(rcu, struct unix_gid, rcu);
>>> + struct cache_head *item = &ug->h;
>>> +
>>> if (test_bit(CACHE_VALID, &item->flags) &&
>>> !test_bit(CACHE_NEGATIVE, &item->flags))
>>> put_group_info(ug->gi);
>>> - kfree_rcu(ug, rcu);
>>> + kfree(ug);
>>> +}
>>> +
>>> +static void unix_gid_put(struct kref *kref)
>>> +{
>>> + struct cache_head *item = container_of(kref, struct cache_head, ref);
>>> + struct unix_gid *ug = container_of(item, struct unix_gid, h);
>>> +
>>> + call_rcu(&ug->rcu, unix_gid_free);
>>> }
>>>
>>> static int unix_gid_match(struct cache_head *corig, struct cache_head *cnew)
>>> --
>>> 2.39.2
>>>
>>
>> --
>> Chuck Lever
>>
>>
>
> --
> Jeff Layton <[email protected]>

--
Chuck Lever