[PATCH] mt76: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

[Felix Fietkau]

On 2021-02-12 03:13, Shuah Khan wrote:
> ieee80211_find_sta_by_ifaddr() must be called under the RCU lock and
> the resulting pointer is only valid under RCU lock as well.
> 
> Fix mt76_check_sta() to hold RCU read lock before it calls
> ieee80211_find_sta_by_ifaddr() and release it when the resulting
> pointer is no longer needed.
> 
> 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 at linuxfoundation.org>
If I'm not mistaken, this patch is unnecessary. mt76_check_sta is only
called from mt76_rx_poll_complete, which itself is only called under RCU
lock.

- Felix