[PATCH v2] 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>
---
Changes since v1:
- v1 also included fix to ath10k_wmi_tlv_parse_peer_stats_info()
  RCU wrn which was already fixed. v2 drops that and fixes just
  ath10k_wmi_event_tdls_peer()
 
 drivers/net/wireless/ath/ath10k/wmi-tlv.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath10k/wmi-tlv.c b/drivers/net/wireless/ath/ath10k/wmi-tlv.c
index bfdd017f1405..d97b33f789e4 100644
--- 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);
 }
 

-- 
2.27.0

Shuah Khan [off-list ref] 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 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 <redacted>

Patch applied to ath-next branch of ath.git, thanks.

09078368d516 ath10k: hold RCU lock when calling ieee80211_find_sta_by_ifaddr()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20210210212107.40373-1-skhan@linuxfoundation.org/

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