wifi: ath11k: fix gtk offload status event locking

The ath11k active pdevs are protected by RCU but the gtk offload status
event handling code calling ath11k_mac_get_arvif_by_vdev_id() was not
marked as a read-side critical section.

Mark the code in question as an RCU read-side critical section to avoid
any potential use-after-free issues.

Compile tested only.

Fixes: a16d9b50 ("ath11k: support GTK rekey offload")
Cc: stable@vger.kernel.org      # 5.18
Cc: Carl Huang <quic_cjhuang@quicinc.com>
Signed-off-by: Johan Hovold <johan+linaro@kernel.org>
Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20231019155342.31631-1-johan+linaro@kernel.org

drivers/net/wireless/ath/ath11k/wmi.c

@@ -8618,12 +8618,13 @@ static void ath11k_wmi_gtk_offload_status_event(struct ath11k_base *ab,
 		return;
 	}
 
+	rcu_read_lock();
+
 	arvif = ath11k_mac_get_arvif_by_vdev_id(ab, ev->vdev_id);
 	if (!arvif) {
 		ath11k_warn(ab, "failed to get arvif for vdev_id:%d\n",
 			    ev->vdev_id);
-		kfree(tb);
-		return;
+		goto exit;
 	}
 
 	ath11k_dbg(ab, ATH11K_DBG_WMI, "event gtk offload refresh_cnt %d\n",
@@ -8640,6 +8641,8 @@ static void ath11k_wmi_gtk_offload_status_event(struct ath11k_base *ab,
 
 	ieee80211_gtk_rekey_notify(arvif->vif, arvif->bssid,
 				   (void *)&replay_ctr_be, GFP_ATOMIC);
+exit:
+	rcu_read_unlock();
 
 	kfree(tb);
 }