linux-kernel - [PATCH AUTOSEL 6.12 03/29] wifi: cfg80211: clear link ID from bitmap during link delete after clean up

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Message-Id: <20241220171130.511389-3-sashal@kernel.org>
Date: Fri, 20 Dec 2024 12:11:04 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Aditya Kumar Singh <quic_adisi@...cinc.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Sasha Levin <sashal@...nel.org>,
	johannes@...solutions.net,
	linux-wireless@...r.kernel.org
Subject: [PATCH AUTOSEL 6.12 03/29] wifi: cfg80211: clear link ID from bitmap during link delete after clean up

From: Aditya Kumar Singh <quic_adisi@...cinc.com>

[ Upstream commit b5c32ff6a3a38c74facdd1fe34c0d709a55527fd ]

Currently, during link deletion, the link ID is first removed from the
valid_links bitmap before performing any clean-up operations. However, some
functions require the link ID to remain in the valid_links bitmap. One
such example is cfg80211_cac_event(). The flow is -

nl80211_remove_link()
    cfg80211_remove_link()
        ieee80211_del_intf_link()
            ieee80211_vif_set_links()
                ieee80211_vif_update_links()
                    ieee80211_link_stop()
                        cfg80211_cac_event()

cfg80211_cac_event() requires link ID to be present but it is cleared
already in cfg80211_remove_link(). Ultimately, WARN_ON() is hit.

Therefore, clear the link ID from the bitmap only after completing the link
clean-up.

Signed-off-by: Aditya Kumar Singh <quic_adisi@...cinc.com>
Link: https://patch.msgid.link/20241121-mlo_dfs_fix-v2-1-92c3bf7ab551@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@...el.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 net/mac80211/cfg.c  | 8 +++++++-
 net/wireless/util.c | 3 +--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 6dfc61a9acd4..d589ea12e596 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -4993,10 +4993,16 @@ static void ieee80211_del_intf_link(struct wiphy *wiphy,
 				    unsigned int link_id)
 {
 	struct ieee80211_sub_if_data *sdata = IEEE80211_WDEV_TO_SUB_IF(wdev);
+	u16 new_links = wdev->valid_links & ~BIT(link_id);
 
 	lockdep_assert_wiphy(sdata->local->hw.wiphy);
 
-	ieee80211_vif_set_links(sdata, wdev->valid_links, 0);
+	/* During the link teardown process, certain functions require the
+	 * link_id to remain in the valid_links bitmap. Therefore, instead
+	 * of removing the link_id from the bitmap, pass a masked value to
+	 * simulate as if link_id does not exist anymore.
+	 */
+	ieee80211_vif_set_links(sdata, new_links, 0);
 }
 
 static int
diff --git a/net/wireless/util.c b/net/wireless/util.c
index f49b55724f83..18585b1416c6 100644
--- a/net/wireless/util.c
+++ b/net/wireless/util.c
@@ -2843,10 +2843,9 @@ void cfg80211_remove_link(struct wireless_dev *wdev, unsigned int link_id)
 		break;
 	}
 
-	wdev->valid_links &= ~BIT(link_id);
-
 	rdev_del_intf_link(rdev, wdev, link_id);
 
+	wdev->valid_links &= ~BIT(link_id);
 	eth_zero_addr(wdev->links[link_id].addr);
 }
 
-- 
2.39.5