netdev - Re: [PATCH net] cls_bpf: don't decrement net's refcount when offload fails

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Message-Id: <20171128.155009.643947779652971751.davem@davemloft.net>
Date:   Tue, 28 Nov 2017 15:50:09 -0500 (EST)
From:   David Miller <davem@...emloft.net>
To:     daniel@...earbox.net
Cc:     jakub.kicinski@...ronome.com, netdev@...r.kernel.org,
        oss-drivers@...ronome.com, xiyou.wangcong@...il.com
Subject: Re: [PATCH net] cls_bpf: don't decrement net's refcount when
 offload fails

From: Daniel Borkmann <daniel@...earbox.net>
Date: Mon, 27 Nov 2017 22:09:33 +0100

> On 11/27/2017 08:11 PM, Jakub Kicinski wrote:
>> When cls_bpf offload was added it seemed like a good idea to
>> call cls_bpf_delete_prog() instead of extending the error
>> handling path, since the software state is fully initialized
>> at that point.  This handling of errors without jumping to
>> the end of the function is error prone, as proven by later
>> commit missing that extra call to __cls_bpf_delete_prog().
>> 
>> __cls_bpf_delete_prog() is now expected to be invoked with
>> a reference on exts->net or the field zeroed out.  The call
>> on the offload's error patch does not fullfil this requirement,
>> leading to each error stealing a reference on net namespace.
>> 
>> Create a function undoing what cls_bpf_set_parms() did and
>> use it from __cls_bpf_delete_prog() and the error path.
>> 
>> Fixes: aae2c35ec892 ("cls_bpf: use tcf_exts_get_net() before call_rcu()")
>> Signed-off-by: Jakub Kicinski <jakub.kicinski@...ronome.com>
>> Reviewed-by: Simon Horman <simon.horman@...ronome.com>
> 
> Fix looks good to me, thanks Jakub! If Dave wants to take
> it directly:
> 
> Acked-by: Daniel Borkmann <daniel@...earbox.net>

Applied and queued up for -stable, thanks everyone.