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From f4f155e5ec04d381b2f0870817d93dbdc259aa63 Mon Sep 17 00:00:00 2001
From: Sara Sharon <sara.sharon@intel.com>
Date: Tue, 19 Dec 2017 09:19:32 +0200
Subject: [PATCH] iwlwifi: mvm: take RCU lock before dereferencing
Git-commit: f4f155e5ec04d381b2f0870817d93dbdc259aa63
Patch-mainline: v4.17-rc1
References: FATE#326294

RCU isn't properly locked.

Fixes: 46d372af9935 ("iwlwifi: mvm: rs: new rate scale API - add FW notifications")
Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c b/drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c
index 55d1274c6092..fb5745660509 100644
--- a/drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c
+++ b/drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c
@@ -234,13 +234,15 @@ void iwl_mvm_tlc_update_notif(struct iwl_mvm *mvm, struct iwl_rx_packet *pkt)
 	struct iwl_mvm_sta *mvmsta;
 	struct iwl_lq_sta_rs_fw *lq_sta;
 
+	rcu_read_lock();
+
 	notif = (void *)pkt->data;
 	mvmsta = iwl_mvm_sta_from_staid_rcu(mvm, notif->sta_id);
 
 	if (!mvmsta) {
 		IWL_ERR(mvm, "Invalid sta id (%d) in FW TLC notification\n",
 			notif->sta_id);
-		return;
+		goto out;
 	}
 
 	lq_sta = &mvmsta->lq_sta.rs_fw;
@@ -251,6 +253,8 @@ void iwl_mvm_tlc_update_notif(struct iwl_mvm *mvm, struct iwl_rx_packet *pkt)
 		IWL_DEBUG_RATE(mvm, "new rate_n_flags: 0x%X\n",
 			       lq_sta->last_rate_n_flags);
 	}
+out:
+	rcu_read_unlock();
 }
 
 void rs_fw_rate_init(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
-- 
2.19.2