netdev - Re: [PATCH net 0/2] net/sched: cls

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Message-ID: <21a8c84d-6a2e-bb84-e980-64437f2f1f16@mojatatu.com>
Date:   Fri, 20 Dec 2019 07:14:58 -0500
From:   Jamal Hadi Salim <jhs@...atatu.com>
To:     David Miller <davem@...emloft.net>, dcaratti@...hat.com
Cc:     netdev@...r.kernel.org, xiyou.wangcong@...il.com, jiri@...nulli.us,
        vladbu@...lanox.com, mrv@...atatu.com
Subject: Re: [PATCH net 0/2] net/sched: cls_u32: fix refcount leak

On 2019-12-19 8:53 p.m., David Miller wrote:
> From: Davide Caratti <dcaratti@...hat.com>
> Date: Wed, 18 Dec 2019 00:00:03 +0100
> 
>> a refcount leak in the error path of u32_change() has been recently
>> introduced. It can be observed with the following commands:
>   ...
>> they all legitimately return -EINVAL; however, they leave semi-configured
>> filters at eth0 tc ingress:
>   ...
>> With older kernels, filters were unconditionally considered empty (and
>> thus de-refcounted) on the error path of ->change().
>> After commit 8b64678e0af8 ("net: sched: refactor tp insert/delete for
>> concurrent execution"), filters were considered empty when the walk()
>> function didn't set 'walker.stop' to 1.
>> Finally, with commit 6676d5e416ee ("net: sched: set dedicated tcf_walker
>> flag when tp is empty"), tc filters are considered empty unless the walker
>> function is called with a non-NULL handle. This last change doesn't fit
>> cls_u32 design, because at least the "root hnode" is (almost) always
>> non-NULL, as it's allocated in u32_init().
>>
>> - patch 1/2 is a proposal to restore the original kernel behavior, where
>>    no filter was installed in the error path of u32_change().
>> - patch 2/2 adds tdc selftests that can be ued to verify the correct
>>    behavior of u32 in the error path of ->change().
> 
> Series applied, thanks.
> 

There is still an ongoing discussion on this patch set...

cheers,
jamal