# Re: \[PATCH\] Revert "ath9k: fix ath\_tx\_process\_buffer() potential null ptr dereference"

- From: Kalle Valo \<hidden\>
- Date: 2021-02-18 06:41:40 
- List: netdev
- Page: https://ratatoskr.run/netdev/2021/02/6272666
- Thread: https://ratatoskr.run/linux-wireless/2021/02/6272357/t.md

```text
Shuah Khan [ref] 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 <redacted>

Thanks. I added the commit id and Fixes tag to the commit log, see the new version above.

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210217211801.22540-1-skhan@linuxfoundation.org/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

```