Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] Revert "ath9k: fix ath_tx_process_buffer() potential null
 ptr dereference"
To:     Kalle Valo <kvalo@codeaurora.org>
Cc:     davem@davemloft.net, kuba@kernel.org, nbd@nbd.name,
        ath9k-devel@qca.qualcomm.com, linux-wireless@vger.kernel.org,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20210217211801.22540-1-skhan@linuxfoundation.org>
 <20210218062333.37872C43462@smtp.codeaurora.org>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <18c2b014-406f-1976-d3aa-354dc285f134@linuxfoundation.org>
Date:   Thu, 18 Feb 2021 07:02:59 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.6.1
MIME-Version: 1.0
In-Reply-To: <20210218062333.37872C43462@smtp.codeaurora.org>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 2/17/21 11:23 PM, Kalle Valo wrote:
> Shuah Khan <skhan@linuxfoundation.org> wrote:
> 
>> This reverts commit a56c14bb21b296fb6d395164ab62ef2e419e5069.
>>
>> ath_tx_process_buffer() doesn't dereference or check sta and passes it
>> to ath_tx_complete_aggr() and ath_tx_complete_buf().
>>
>> ath_tx_complete_aggr() checks the pointer before use. No problem here.
>>
>> ath_tx_complete_buf() doesn't check or dereference sta and passes it on
>> to ath_tx_complete(). ath_tx_complete() doesn't check or dereference sta,
>> but assigns it to tx_info->status.status_driver_data[0]
>>
>> ath_tx_complete_buf() is called from ath_tx_complete_aggr() passing
>> null ieee80211_sta pointer.
>>
>> There is a potential for dereference later on, if and when the
>> tx_info->status.status_driver_data[0]is referenced. In addition, the
>> rcu read lock might be released before referencing the contents.
>>
>> ath_tx_complete_buf() should be fixed to check sta perhaps? Worth
>> looking into.
>>
>> Reverting this patch because it doesn't solve the problem and introduces
>> memory leak by skipping buffer completion if the pointer (sta) is NULL.
>>
>> Fixes: a56c14bb21b2 ("ath9k: fix ath_tx_process_buffer() potential null ptr dereference")
>> Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
>> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
> 
> Thanks. I added the commit id and Fixes tag to the commit log, see the new version above.
> 

Thanks. Sorry for forgetting the Fixes tag.

thanks,
-- Shuah