ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

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 ath10k_wmi_tlv_op_pull_peer_stats_info() to hold RCU 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().

Link: https://lore.kernel.org/linux-wireless/7230c9e5-2632-b77e-c4f9-10eca557a5bb@linuxfoundation.org/
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210210212107.40373-1-skhan@linuxfoundation.org

diff --git a/drivers/net/wireless/ath/ath10k/wmi-tlv.c b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
index bfdd017..d97b33f 100644 (file)
--- a/drivers/net/wireless/ath/ath10k/wmi-tlv.c
+++ b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
@@ -576,13 +576,13 @@ static void ath10k_wmi_event_tdls_peer(struct ath10k *ar, struct sk_buff *skb)
        case WMI_TDLS_TEARDOWN_REASON_TX:
        case WMI_TDLS_TEARDOWN_REASON_RSSI:
        case WMI_TDLS_TEARDOWN_REASON_PTR_TIMEOUT:
+               rcu_read_lock();
                station = ieee80211_find_sta_by_ifaddr(ar->hw,
                                                       ev->peer_macaddr.addr,
                                                       NULL);
                if (!station) {
                        ath10k_warn(ar, "did not find station from tdls peer event");
-                       kfree(tb);
-                       return;
+                       goto exit;
                }
                arvif = ath10k_get_arvif(ar, __le32_to_cpu(ev->vdev_id));
                ieee80211_tdls_oper_request(
@@ -593,6 +593,9 @@ static void ath10k_wmi_event_tdls_peer(struct ath10k *ar, struct sk_buff *skb)
                                        );
                break;
        }
+
+exit:
+       rcu_read_unlock();
        kfree(tb);
 }