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Date: Mon, 1 Jan 2024 10:42:54 -0800
From: Cong Wang <xiyou.wangcong@gmail.com>
To: Lin Ma <linma@zju.edu.cn>
Cc: jhs@mojatatu.com, jiri@resnulli.us, davem@davemloft.net,
	edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
	netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH net-next v2] net/sched: cls_api: complement
 tcf_tfilter_dump_policy
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References: <20231228064358.3042747-1-linma@zju.edu.cn>
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On Thu, Dec 28, 2023 at 02:43:58PM +0800, Lin Ma wrote:
> In function `tc_dump_tfilter`, the attributes array is parsed via
> tcf_tfilter_dump_policy which only describes TCA_DUMP_FLAGS. However,
> the NLA TCA_CHAIN is also accessed with `nla_get_u32`.
> 
> The access to TCA_CHAIN is introduced in commit 5bc1701881e3 ("net:
> sched: introduce multichain support for filters") and no nla_policy is
> provided for parsing at that point. Later on, tcf_tfilter_dump_policy is
> introduced in commit f8ab1807a9c9 ("net: sched: introduce terse dump
> flag") while still ignoring the fact that TCA_CHAIN needs a check. This
> patch does that by complementing the policy to allow the access
> discussed here can be safe as other cases just choose rtm_tca_policy as
> the parsing policy.
> 

This patch looks good but you could use NLA_POLICY_MAX() to validate
TCA_CHAIN while you are on it.

Thanks.