wifi: cfg80211: clear link ID from bitmap during link delete after clean up

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@quicinc.com>
Link: https://patch.msgid.link/20241121-mlo_dfs_fix-v2-1-92c3bf7ab551@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 1dd61c9bb8f1ba717bfe655add7ccdfe335e765a..506b7c4697112450dbb4abd3802065b531532688 100644 (file)
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -5046,10 +5046,16 @@ 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 040d62051eb96ea52ba301f0767d2e4e4ba51e0b..65c8e47246b7c3889e9c2faf0c0b508c426ee513 100644 (file)
--- 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);
 }