[PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Vasily Averin]

ipmr_free_table() calls unregister_netdevice_many() inside
and changes net_todo_list protected by rtnl_lock

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 net/ipv6/ip6mr.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c
index 74ceb73..9108636 100644
--- a/net/ipv6/ip6mr.c
+++ b/net/ipv6/ip6mr.c
@@ -250,7 +250,9 @@ static int __net_init ip6mr_rules_init(struct net *net)
 	return 0;
 
 err2:
+	rtnl_lock();
 	ip6mr_free_table(mrt);
+	rtnl_unlock();
 err1:
 	fib_rules_unregister(ops);
 	return err;
-- 
1.9.1

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Cong Wang]

On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
> ipmr_free_table() calls unregister_netdevice_many() inside
> and changes net_todo_list protected by rtnl_lock
>

Did you see any real bug?

ipmr_free_table() is called in failure path, in this case there is no
device registered yet, so unregister should be just a nop?

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Vasily Averin]

On 07.07.2015 20:13, Cong Wang wrote:
> On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>> ipmr_free_table() calls unregister_netdevice_many() inside
>> and changes net_todo_list protected by rtnl_lock
> 
> Did you see any real bug?

No, it was result of manual code review.

> ipmr_free_table() is called in failure path, in this case there is no
> device registered yet, so unregister should be just a nop?

However may be it's better to mark this place for future anyway?

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Cong Wang]

On Tue, Jul 7, 2015 at 10:25 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
> On 07.07.2015 20:13, Cong Wang wrote:
>> On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>> ipmr_free_table() calls unregister_netdevice_many() inside
>>> and changes net_todo_list protected by rtnl_lock
>>
>> Did you see any real bug?
>
> No, it was result of manual code review.
>
>> ipmr_free_table() is called in failure path, in this case there is no
>> device registered yet, so unregister should be just a nop?
>
> However may be it's better to mark this place for future anyway?

Then add a comment there. ;)

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Vasily Averin]

On 07.07.2015 20:30, Cong Wang wrote:
> On Tue, Jul 7, 2015 at 10:25 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>> On 07.07.2015 20:13, Cong Wang wrote:
>>> On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>>> ipmr_free_table() calls unregister_netdevice_many() inside
>>>> and changes net_todo_list protected by rtnl_lock
>>>
>>> Did you see any real bug?
>>
>> No, it was result of manual code review.
>>
>>> ipmr_free_table() is called in failure path, in this case there is no
>>> device registered yet, so unregister should be just a nop?
>>
>> However may be it's better to mark this place for future anyway?
> 
> Then add a comment there. ;)

As you can see I'm not familiar with this code,
so I would like to ask you to do it. :)

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Vasily Averin]

On 07.07.2015 20:53, Vasily Averin wrote:
> On 07.07.2015 20:30, Cong Wang wrote:
>> On Tue, Jul 7, 2015 at 10:25 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>> On 07.07.2015 20:13, Cong Wang wrote:
>>>> On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>>>> ipmr_free_table() calls unregister_netdevice_many() inside
>>>>> and changes net_todo_list protected by rtnl_lock
>>>>
>>>> Did you see any real bug?
>>>
>>> No, it was result of manual code review.
>>>
>>>> ipmr_free_table() is called in failure path, in this case there is no
>>>> device registered yet, so unregister should be just a nop?
>>>
>>> However may be it's better to mark this place for future anyway?
>>
>> Then add a comment there. ;)
> 
> As you can see I'm not familiar with this code,
> so I would like to ask you to do it. :)

Seems I've found a better idea:
to add ASSERT_RTNL() into unregister_netdevice_many()

Re: [PATCH 3/3] ipmr_free_table() should be called under taken rtnl_lock

[Vasily Averin]

On 08.07.2015 13:29, Vasily Averin wrote:
> On 07.07.2015 20:53, Vasily Averin wrote:
>> On 07.07.2015 20:30, Cong Wang wrote:
>>> On Tue, Jul 7, 2015 at 10:25 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>>> On 07.07.2015 20:13, Cong Wang wrote:
>>>>> On Tue, Jul 7, 2015 at 8:53 AM, Vasily Averin <vvs@virtuozzo.com> wrote:
>>>>>> ipmr_free_table() calls unregister_netdevice_many() inside
>>>>>> and changes net_todo_list protected by rtnl_lock
>>>>>
>>>>> Did you see any real bug?
>>>>
>>>> No, it was result of manual code review.
>>>>
>>>>> ipmr_free_table() is called in failure path, in this case there is no
>>>>> device registered yet, so unregister should be just a nop?
>>>>
>>>> However may be it's better to mark this place for future anyway?
>>>
>>> Then add a comment there. ;)
>>
>> As you can see I'm not familiar with this code,
>> so I would like to ask you to do it. :)
> 
> Seems I've found a better idea:
> to add ASSERT_RTNL() into unregister_netdevice_many()

It was done already,
there is ASSERT_RTNL() in rollback_registered_many() called from unregister_netdevice_many().

Please drop this patch, seems it isn't required.