netdev - Re: [PATCH] net: sched: fix a error path in fw

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Date:   Mon, 5 Dec 2022 10:36:00 +0800
From:   liqiong <liqiong@...china.com>
To:     Cong Wang <xiyou.wangcong@...il.com>
Cc:     Jamal Hadi Salim <jhs@...atatu.com>, Jiri Pirko <jiri@...nulli.us>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yu Zhe <yuzhe@...china.com>
Subject: Re: [PATCH] net: sched: fix a error path in fw_change()



在 2022年12月04日 03:46, Cong Wang 写道:
> On Thu, Dec 01, 2022 at 11:15:32PM +0800, Li Qiong wrote:
>> The 'pfp' pointer could be null if can't find the target filter.
>> Check 'pfp' pointer and fix this error path.
> Did you see any actual kernel crash? And do you have a reproducer too?
> Please include them if you do.
Found this by  'smatch' tool,  I check and find it may be a real problem at the risk
of NULL pointer. Like 'fw_delete()', It checks  'pfp' and 'pfp == f' too.
 



>
>> Signed-off-by: Li Qiong <liqiong@...china.com>
>> ---
>>  net/sched/cls_fw.c | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/net/sched/cls_fw.c b/net/sched/cls_fw.c
>> index a32351da968c..b898e4a81146 100644
>> --- a/net/sched/cls_fw.c
>> +++ b/net/sched/cls_fw.c
>> @@ -289,6 +289,12 @@ static int fw_change(struct net *net, struct sk_buff *in_skb,
>>  			if (pfp == f)
>>  				break;
>>  
>> +		if (!pfp) {
>> +			tcf_exts_destroy(&fnew->exts);
>> +			kfree(fnew);
>> +			return err;
>
> BTW, err is 0 here, you have to set some error here.
You are right,  It should return  '-EINVAL'  -- can't get the target filter.



>
> Thanks.