linux-kernel - [PATCH 5.4 36/38] wifi: cfg80211: update hidden BSSes to avoid WARN

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Message-Id: <20221013175145.450004794@linuxfoundation.org>
Date:   Thu, 13 Oct 2022 19:52:37 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Sönke Huster <shuster@...moo.tu-darmstadt.de>,
        Johannes Berg <johannes.berg@...el.com>
Subject: [PATCH 5.4 36/38] wifi: cfg80211: update hidden BSSes to avoid WARN_ON

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

commit c90b93b5b782891ebfda49d4e5da36632fefd5d1 upstream.

When updating beacon elements in a non-transmitted BSS,
also update the hidden sub-entries to the same beacon
elements, so that a future update through other paths
won't trigger a WARN_ON().

The warning is triggered because the beacon elements in
the hidden BSSes that are children of the BSS should
always be the same as in the parent.

Reported-by: Sönke Huster <shuster@...moo.tu-darmstadt.de>
Tested-by: Sönke Huster <shuster@...moo.tu-darmstadt.de>
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/wireless/scan.c |   31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -1099,6 +1099,23 @@ struct cfg80211_non_tx_bss {
 	u8 bssid_index;
 };
 
+static void cfg80211_update_hidden_bsses(struct cfg80211_internal_bss *known,
+					 const struct cfg80211_bss_ies *new_ies,
+					 const struct cfg80211_bss_ies *old_ies)
+{
+	struct cfg80211_internal_bss *bss;
+
+	/* Assign beacon IEs to all sub entries */
+	list_for_each_entry(bss, &known->hidden_list, hidden_list) {
+		const struct cfg80211_bss_ies *ies;
+
+		ies = rcu_access_pointer(bss->pub.beacon_ies);
+		WARN_ON(ies != old_ies);
+
+		rcu_assign_pointer(bss->pub.beacon_ies, new_ies);
+	}
+}
+
 static bool
 cfg80211_update_known_bss(struct cfg80211_registered_device *rdev,
 			  struct cfg80211_internal_bss *known,
@@ -1122,7 +1139,6 @@ cfg80211_update_known_bss(struct cfg8021
 			kfree_rcu((struct cfg80211_bss_ies *)old, rcu_head);
 	} else if (rcu_access_pointer(new->pub.beacon_ies)) {
 		const struct cfg80211_bss_ies *old;
-		struct cfg80211_internal_bss *bss;
 
 		if (known->pub.hidden_beacon_bss &&
 		    !list_empty(&known->hidden_list)) {
@@ -1150,16 +1166,7 @@ cfg80211_update_known_bss(struct cfg8021
 		if (old == rcu_access_pointer(known->pub.ies))
 			rcu_assign_pointer(known->pub.ies, new->pub.beacon_ies);
 
-		/* Assign beacon IEs to all sub entries */
-		list_for_each_entry(bss, &known->hidden_list, hidden_list) {
-			const struct cfg80211_bss_ies *ies;
-
-			ies = rcu_access_pointer(bss->pub.beacon_ies);
-			WARN_ON(ies != old);
-
-			rcu_assign_pointer(bss->pub.beacon_ies,
-					   new->pub.beacon_ies);
-		}
+		cfg80211_update_hidden_bsses(known, new->pub.beacon_ies, old);
 
 		if (old)
 			kfree_rcu((struct cfg80211_bss_ies *)old, rcu_head);
@@ -1798,6 +1805,8 @@ cfg80211_update_notlisted_nontrans(struc
 	} else {
 		old = rcu_access_pointer(nontrans_bss->beacon_ies);
 		rcu_assign_pointer(nontrans_bss->beacon_ies, new_ies);
+		cfg80211_update_hidden_bsses(bss_from_pub(nontrans_bss),
+					     new_ies, old);
 		rcu_assign_pointer(nontrans_bss->ies, new_ies);
 		if (old)
 			kfree_rcu((struct cfg80211_bss_ies *)old, rcu_head);