[PATCH v6 1/3] wifi: ath12k: prepare vif data structure for MLO handling

[Aditya Kumar Singh]

On 8/6/24 17:58, Kalle Valo wrote:
> Rameshkumar Sundaram <quic_ramess at quicinc.com> writes:
> 
>> From: Sriram R <quic_srirrama at quicinc.com>
>>
>> To prepare the driver for MLO support, split the driver vif
>> data structure to scale for multiple links. This requires changing
>> the use of arvif to per link and not per hw which can now
>> comprise of multiple links.
>> Also since most configurations from mac80211 are done per link, do refactoring
>> of the driver functions to apply these configurations at link level.
> 
> Something I noticed while reviewing this patchset:
> 
>>   static int ath12k_mac_op_add_interface(struct ieee80211_hw *hw,
>>   				       struct ieee80211_vif *vif)
>>   {
>> -	struct ath12k_vif *arvif = ath12k_vif_to_arvif(vif);
>> +	struct ath12k_hw *ah = ath12k_hw_to_ah(hw);
>> +	struct ath12k_vif *ahvif = ath12k_vif_to_ahvif(vif);
>> +	struct ath12k_link_vif *arvif;
>>   	int i;
>>   
>> -	memset(arvif, 0, sizeof(*arvif));
>> +	mutex_lock(&ah->conf_mutex);
>> +	memset(ahvif, 0, sizeof(*ahvif));
> 
> Here we are we clearing ahvif so ahvif->deflink is NULL.

deflink is not a pointer member. It is statically defined inside ahvif. 
So basically this memsets the whole deflink memory region to 0.
> 
>> -	arvif->vif = vif;
>> +	ahvif->ah = ah;
>> +	ahvif->vif = vif;
>> +	arvif = &ahvif->deflink;
> 
> So here we assign arvif to NULL.

This would be a still valid pointer.
> 
>> +	arvif->ahvif = ahvif;
> 
> And because arvif is NULL this is a null pointer reference, right? Or am
> I missing something?

So since it is valid pointer, this is not a NULL pointer de-reference.

-- 
Aditya