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From: Haimin Zhang <tcs.kernel@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>,
	vinicius.gomes@intel.com, jhs@mojatatu.com,
	xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net,
	kuba@kernel.org, netdev@vger.kernel.org
Cc: Haimin Zhang <tcs_kernel@tencent.com>
Subject: Re: [PATCH] net:sched fix array-index-out-of-bounds in taprio_change
Date: Wed, 11 Aug 2021 16:36:57 +0800	[thread overview]
Message-ID: <e965fed3-89c3-ff58-a678-dd715a2b9fcd@gmail.com> (raw)
In-Reply-To: <303b095e-3342-9461-16ae-86d0923b7dc7@gmail.com>



在 2021/8/11 15:44, Eric Dumazet 写道:
> 
> 
> On 8/11/21 7:10 AM, tcs.kernel@gmail.com wrote:
>> From: Haimin Zhang <tcs_kernel@tencent.com>
>>
>> syzbot report an array-index-out-of-bounds in taprio_change
>> index 16 is out of range for type '__u16 [16]'
>> that's because mqprio->num_tc is lager than TC_MAX_QUEUE,so we check
>> the return value of netdev_set_num_tc.
>>
>> Reported-by: syzbot+2b3e5fb6c7ef285a94f6@syzkaller.appspotmail.com
>> Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
>> ---
>>   net/sched/sch_taprio.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
>> index 9c79374..1ab2fc9 100644
>> --- a/net/sched/sch_taprio.c
>> +++ b/net/sched/sch_taprio.c
>> @@ -1513,7 +1513,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
>>   	taprio_set_picos_per_byte(dev, q);
>>   
>>   	if (mqprio) {
>> -		netdev_set_num_tc(dev, mqprio->num_tc);
>> +		err = netdev_set_num_tc(dev, mqprio->num_tc);
>> +		if (err)
>> +			goto free_sched;
>>   		for (i = 0; i < mqprio->num_tc; i++)
>>   			netdev_set_tc_queue(dev, i,
>>   					    mqprio->count[i],
>>
> 
> When was the bug added ?
> 
> Hint: Please provide a Fixes: tag
> 
> taprio_parse_mqprio_opt() already checks :
> 
> /* Verify num_tc is not out of max range */
> if (qopt->num_tc > TC_MAX_QUEUE) {
>      NL_SET_ERR_MSG(extack, "Number of traffic classes is outside valid range");
>      return -EINVAL;
> }
> 
> So what is happening exactly ?
> 
> 
> 
> 
syzkaller reported this problem,the log shows mqprio->count[16] is accessed.
here is the log
https://syzkaller.appspot.com/bug?id=3a3677d4e7539ec5e671a81e32882ad40b5f7b64

the added check logic is hurtlessness,and netdev_set_num_tc does have a 
return value.

  parent reply	other threads:[~2021-08-11  8:37 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-11  5:10 tcs.kernel
2021-08-11  7:44 ` Eric Dumazet
2021-08-11  8:30   ` Pavel Skripkin
2021-08-11  8:35     ` Pavel Skripkin
2021-08-11  8:36   ` Haimin Zhang [this message]
2021-08-30  2:09     ` Haimin Zhang
2021-08-30 16:10       ` Jakub Kicinski
2021-08-12 17:53 ` Jakub Kicinski
  -- strict thread matches above, loose matches on Subject: below --
2021-08-11  4:09 tcs.kernel

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