linux-hardening - Re: [RESEND PATCH net 1/2] iavf: Fix use-after-free in free

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Message-ID: <ff2e0a06-abbb-213a-40ed-20c8e8b2f429@sangfor.com.cn>
Date:   Wed, 19 Apr 2023 09:11:37 +0800
From:   Ding Hui <dinghui@...gfor.com.cn>
To:     Simon Horman <simon.horman@...igine.com>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, intel-wired-lan@...ts.osuosl.org,
        jesse.brandeburg@...el.com, anthony.l.nguyen@...el.com,
        keescook@...omium.org, grzegorzx.szczurek@...el.com,
        mateusz.palczewski@...el.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org,
        pengdonglin@...gfor.com.cn, huangcun@...gfor.com.cn
Subject: Re: [RESEND PATCH net 1/2] iavf: Fix use-after-free in free_netdev

On 2023/4/19 3:48, Simon Horman wrote:
> Hi Ding Hui,
> 
> On Mon, Apr 17, 2023 at 03:40:15PM +0800, Ding Hui wrote:
>> We do netif_napi_add() for all allocated q_vectors[], but potentially
>> do netif_napi_del() for part of them, then kfree q_vectors and lefted
> 
> nit: lefted -> leave
> 

Thanks, I'll update in v2.

>> invalid pointers at dev->napi_list.
>>
>> If num_active_queues is changed to less than allocated q_vectors[] by
>> unexpected, when iavf_remove, we might see UAF in free_netdev like this:
>>

...

>>
>> Fix it by letting netif_napi_del() match to netif_napi_add().
>>
>> Signed-off-by: Ding Hui <dinghui@...gfor.com.cn>
>> Cc: Donglin Peng <pengdonglin@...gfor.com.cn>
>> CC: Huang Cun <huangcun@...gfor.com.cn>
> 
> as this is a fix it probably should have a fixes tag.
> I wonder if it should be:
> 
> Fixes: cc0529271f23 ("i40evf: don't use more queues than CPUs")

I don't think so.
I searched the git log, and found that the mismatched usage was
introduced since the beginning of i40evf_main.c, so I'll add

Fixes: 5eae00c57f5e ("i40evf: main driver core")

in v2.

> 
> Code change looks good to me.
> 
> Reviewed-by: Simon Horman <simon.horman@...igine.com>
> 

Thanks.

And sorry for you confusion since my RESEND.

>> ---
>>   drivers/net/ethernet/intel/iavf/iavf_main.c | 6 +-----
>>   1 file changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/drivers/net/ethernet/intel/iavf/iavf_main.c b/drivers/net/ethernet/intel/iavf/iavf_main.c
>> index 095201e83c9d..a57e3425f960 100644
>> --- a/drivers/net/ethernet/intel/iavf/iavf_main.c
>> +++ b/drivers/net/ethernet/intel/iavf/iavf_main.c
>> @@ -1849,19 +1849,15 @@ static int iavf_alloc_q_vectors(struct iavf_adapter *adapter)
>>   static void iavf_free_q_vectors(struct iavf_adapter *adapter)
>>   {
>>   	int q_idx, num_q_vectors;
>> -	int napi_vectors;
>>   
>>   	if (!adapter->q_vectors)
>>   		return;
>>   
>>   	num_q_vectors = adapter->num_msix_vectors - NONQ_VECS;
>> -	napi_vectors = adapter->num_active_queues;
>>   
>>   	for (q_idx = 0; q_idx < num_q_vectors; q_idx++) {
>>   		struct iavf_q_vector *q_vector = &adapter->q_vectors[q_idx];
>> -
>> -		if (q_idx < napi_vectors)
>> -			netif_napi_del(&q_vector->napi);
>> +		netif_napi_del(&q_vector->napi);
>>   	}
>>   	kfree(adapter->q_vectors);
>>   	adapter->q_vectors = NULL;
>> -- 
>> 2.17.1
>>
> 

-- 
Thanks,
- Ding Hui