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Message-ID: <4f43fa6c-d68b-11f6-66cc-5ee995d05a6e@nvidia.com>
Date: Sat, 25 Feb 2023 20:10:08 +0200
From: Paul Blakey <paulb@...dia.com>
To: Eric Dumazet <edumazet@...gle.com>
Cc: netdev@...r.kernel.org, Saeed Mahameed <saeedm@...dia.com>,
Paolo Abeni <pabeni@...hat.com>,
Jakub Kicinski <kuba@...nel.org>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
"David S. Miller" <davem@...emloft.net>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Oz Shlomo <ozsh@...dia.com>, Jiri Pirko <jiri@...dia.com>,
Roi Dayan <roid@...dia.com>, Vlad Buslov <vladbu@...dia.com>,
Ido Schimmel <idosch@...dia.com>,
Simon Horman <simon.horman@...igine.com>
Subject: Re: [PATCH net-next v13 3/8] net/sched: flower: Move filter handle
initialization earlier
On 25/02/2023 10:14, Eric Dumazet wrote:
> On Sat, Feb 25, 2023 at 8:54 AM Paul Blakey <paulb@...dia.com> wrote:
>>
>>
>>
>> On 23/02/2023 12:24, Eric Dumazet wrote:
>>> On Fri, Feb 17, 2023 at 11:36 PM Paul Blakey <paulb@...dia.com> wrote:
>>>>
>>>> To support miss to action during hardware offload the filter's
>>>> handle is needed when setting up the actions (tcf_exts_init()),
>>>> and before offloading.
>>>>
>>>> Move filter handle initialization earlier.
>>>>
>>>> Signed-off-by: Paul Blakey <paulb@...dia.com>
>>>> Reviewed-by: Jiri Pirko <jiri@...dia.com>
>>>> Reviewed-by: Simon Horman <simon.horman@...igine.com>
>>>> Reviewed-by: Marcelo Ricardo Leitner <marcelo.leitner@...il.com>
>>>> ---
>>>
>>> Error path is now potentially crashing because net pointer has not
>>> been initialized.
>>>
>>> I plan fixing this issue with the following:
>>>
>>> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>>> index e960a46b05205bb0bca7dc0d21531e4d6a3853e3..475fe222a85566639bac75fc4a95bf649a10357d
>>> 100644
>>> --- a/net/sched/cls_flower.c
>>> +++ b/net/sched/cls_flower.c
>>> @@ -2200,8 +2200,9 @@ static int fl_change(struct net *net, struct
>>> sk_buff *in_skb,
>>> fnew->flags = nla_get_u32(tb[TCA_FLOWER_FLAGS]);
>>>
>>> if (!tc_flags_valid(fnew->flags)) {
>>> + kfree(fnew);
>>> err = -EINVAL;
>>> - goto errout;
>>> + goto errout_tb;
>>> }
>>> }
>>>
>>> @@ -2226,8 +2227,10 @@ static int fl_change(struct net *net, struct
>>> sk_buff *in_skb,
>>> }
>>> spin_unlock(&tp->lock);
>>>
>>> - if (err)
>>> - goto errout;
>>> + if (err) {
>>> + kfree(fnew);
>>> + goto errout_tb;
>>> + }
>>> }
>>> fnew->handle = handle;
>>>
>>> @@ -2337,7 +2340,6 @@ static int fl_change(struct net *net, struct
>>> sk_buff *in_skb,
>>> fl_mask_put(head, fnew->mask);
>>> errout_idr:
>>> idr_remove(&head->handle_idr, fnew->handle);
>>> -errout:
>>> __fl_put(fnew);
>>> errout_tb:
>>> kfree(tb);
>>
>>
>> Notice that the bug was before this patch as well.
>> We init exts->net only in fl_set_parms()->tcf_exts_validate(exts), and
>> before this patch we called __fl_put() on two errors before that (like
>> if tcf_exts_init() failed).
>>
>>
>> Here, its the same, we can't call __fl_put(fnew) till we called
>> fl_set_parms(). So you're missing this "goto errorout_idr":
>>
>>
>> err = tcf_exts_init_ex(&fnew->exts, net, TCA_FLOWER_ACT, 0, tp, handle,
>> !tc_skip_hw(fnew->flags));
>> if (err < 0)
>> goto errout_idr;
>>
>> Thanks,
>> Paul.
>>
>
> The bug I am talking about is triggering because ->net pointer is not
> initialized.
>
> ->net pointer is initialized in tcf_exts_init_ex(), before any error
> can be returned.
Right, so all good!
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