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Date:   Tue, 22 Dec 2020 21:18:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Johannes Berg <johannes.berg@...el.com>,
        Luca Coelho <luciano.coelho@...el.com>,
        Sasha Levin <sashal@...nel.org>,
        linux-wireless@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 119/130] mac80211: disallow band-switch during CSA

From: Johannes Berg <johannes.berg@...el.com>

[ Upstream commit 3660944a37ce73890292571f44f04891834f9044 ]

If the AP advertises a band switch during CSA, we will not have
the right information to continue working with it, since it will
likely (have to) change its capabilities and we don't track any
capability changes at all. Additionally, we store e.g. supported
rates per band, and that information would become invalid.

Since this is a fringe scenario, just disconnect explicitly.

Signed-off-by: Luca Coelho <luciano.coelho@...el.com>
Link: https://lore.kernel.org/r/iwlwifi.20201129172929.0e2327107c06.I461adb07704e056b054a4a7c29b80c95a9f56637@changeid
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/mlme.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
index 17a3a1c938beb..236ddc6b891c2 100644
--- a/net/mac80211/mlme.c
+++ b/net/mac80211/mlme.c
@@ -1334,6 +1334,17 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 		return;
 	}
 
+	if (sdata->vif.bss_conf.chandef.chan->band !=
+	    csa_ie.chandef.chan->band) {
+		sdata_info(sdata,
+			   "AP %pM switches to different band (%d MHz, width:%d, CF1/2: %d/%d MHz), disconnecting\n",
+			   ifmgd->associated->bssid,
+			   csa_ie.chandef.chan->center_freq,
+			   csa_ie.chandef.width, csa_ie.chandef.center_freq1,
+			   csa_ie.chandef.center_freq2);
+		goto lock_and_drop_connection;
+	}
+
 	if (!cfg80211_chandef_usable(local->hw.wiphy, &csa_ie.chandef,
 				     IEEE80211_CHAN_DISABLED)) {
 		sdata_info(sdata,
@@ -1342,9 +1353,7 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 			   csa_ie.chandef.chan->center_freq,
 			   csa_ie.chandef.width, csa_ie.chandef.center_freq1,
 			   csa_ie.chandef.center_freq2);
-		ieee80211_queue_work(&local->hw,
-				     &ifmgd->csa_connection_drop_work);
-		return;
+		goto lock_and_drop_connection;
 	}
 
 	if (cfg80211_chandef_identical(&csa_ie.chandef,
@@ -1429,6 +1438,9 @@ ieee80211_sta_process_chanswitch(struct ieee80211_sub_if_data *sdata,
 			  TU_TO_EXP_TIME((csa_ie.count - 1) *
 					 cbss->beacon_interval));
 	return;
+ lock_and_drop_connection:
+	mutex_lock(&local->mtx);
+	mutex_lock(&local->chanctx_mtx);
  drop_connection:
 	/*
 	 * This is just so that the disconnect flow will know that
-- 
2.27.0

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