Re: [PATCH 2/2] ath9k: fix ath_tx_process_buffer() potential null ptr dereference

[Shuah Khan <skhan@linuxfoundation.org>]

On 2/17/21 12:30 AM, Kalle Valo wrote:
> Shuah Khan <skhan@linuxfoundation.org> writes:
> 
>> On 2/16/21 12:53 AM, Felix Fietkau wrote:
>>>
>>> On 2021-02-16 08:03, Kalle Valo wrote:
>>>> Shuah Khan <skhan@linuxfoundation.org> wrote:
>>>>
>>>>> ath_tx_process_buffer() references ieee80211_find_sta_by_ifaddr()
>>>>> return pointer (sta) outside null check. Fix it by moving the code
>>>>> block under the null check.
>>>>>
>>>>> This problem was found while reviewing code to debug RCU warn from
>>>>> ath10k_wmi_tlv_parse_peer_stats_info() and a subsequent manual audit
>>>>> of other callers of ieee80211_find_sta_by_ifaddr() that don't hold
>>>>> RCU read lock.
>>>>>
>>>>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
>>>>> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
>>>>
>>>> Patch applied to ath-next branch of ath.git, thanks.
>>>>
>>>> a56c14bb21b2 ath9k: fix ath_tx_process_buffer() potential null ptr dereference
>>> I just took another look at this patch, and it is completely bogus.
>>> Not only does the stated reason not make any sense (sta is simply passed
>>> to other functions, not dereferenced without checks), but this also
>>> introduces a horrible memory leak by skipping buffer completion if sta
>>> is NULL.
>>> Please drop it, the code is fine as-is.
>>
>> A comment describing what you said here might be a good addition to this
>> comment block though.
> 
> Shuah, can you send a followup patch which reverts your change and adds
> the comment? I try to avoid rebasing my trees.
> 


I can do that.

thanks,
-- Shuah