wifi: iwlwifi: mvm: fix station link data leak

When we remove the station, we call iwl_mvm_sta_del() which
returns true if we cannot remove it from the firmware yet,
which happens if this is the station ID for the AP station
that's still used because the MAC is still associated.

However, we still must free the link data as the station is
only kept alive in the firmware, in mac80211 and driver the
data structures are destroyed.

To fix that, we need to make iwl_mvm_mld_free_sta_link()
track whether or not the station is still alive in FW, as
otherwise we might reuse the station ID in the meantime and
iwl_mvm_mld_rm_sta_from_fw() would reject the later delete
from the firmware. Add an argument to it for that. Then we
can use the return value of iwl_mvm_sta_del() for that to
fix the issue, and call iwl_mvm_mld_rm_sta_from_fw() only
if we need to not keep the station in FW.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230329100039.1d81d4c71f35.I8fc60ac28ffc1147e9b1250e5e6237b3cb5516ac@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/mld-mac80211.c

@@ -545,7 +545,7 @@ static void iwl_mvm_mld_vif_delete_all_stas(struct iwl_mvm *mvm,
 			continue;
 
 		iwl_mvm_sec_key_remove_ap(mvm, vif, link, i);
-		ret = iwl_mvm_mld_rm_sta_id(mvm, vif, link->ap_sta_id);
+		ret = iwl_mvm_mld_rm_sta_id(mvm, link->ap_sta_id);
 		if (ret)
 			IWL_ERR(mvm, "failed to remove AP station\n");
 

drivers/net/wireless/intel/iwlwifi/mvm/mld-sta.c

@@ -458,6 +458,21 @@ static int iwl_mvm_mld_cfg_sta(struct iwl_mvm *mvm, struct ieee80211_sta *sta,
 	return iwl_mvm_mld_send_sta_cmd(mvm, &cmd);
 }
 
+static void iwl_mvm_mld_free_sta_link(struct iwl_mvm *mvm,
+				      struct iwl_mvm_sta *mvm_sta,
+				      struct iwl_mvm_link_sta *mvm_sta_link,
+				      unsigned int link_id,
+				      bool is_in_fw)
+{
+	RCU_INIT_POINTER(mvm->fw_id_to_mac_id[mvm_sta_link->sta_id],
+			 is_in_fw ? ERR_PTR(-EINVAL) : NULL);
+	RCU_INIT_POINTER(mvm->fw_id_to_link_sta[mvm_sta_link->sta_id], NULL);
+	RCU_INIT_POINTER(mvm_sta->link[link_id], NULL);
+
+	if (mvm_sta_link != &mvm_sta->deflink)
+		kfree_rcu(mvm_sta_link, rcu_head);
+}
+
 static void iwl_mvm_mld_sta_rm_all_sta_links(struct iwl_mvm *mvm,
 					     struct iwl_mvm_sta *mvm_sta)
 {
@@ -471,28 +486,10 @@ static void iwl_mvm_mld_sta_rm_all_sta_links(struct iwl_mvm *mvm,
 		if (!link)
 			continue;
 
-		RCU_INIT_POINTER(mvm->fw_id_to_mac_id[link->sta_id], NULL);
-		RCU_INIT_POINTER(mvm->fw_id_to_link_sta[link->sta_id], NULL);
-		RCU_INIT_POINTER(mvm_sta->link[link_id], NULL);
-
-		if (link != &mvm_sta->deflink)
-			kfree_rcu(link, rcu_head);
+		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, link, link_id, false);
 	}
 }
 
-static void iwl_mvm_mld_free_sta_link(struct iwl_mvm *mvm,
-				      struct iwl_mvm_sta *mvm_sta,
-				      struct iwl_mvm_link_sta *mvm_sta_link,
-				      unsigned int link_id)
-{
-	RCU_INIT_POINTER(mvm->fw_id_to_mac_id[mvm_sta_link->sta_id], NULL);
-	RCU_INIT_POINTER(mvm->fw_id_to_link_sta[mvm_sta_link->sta_id], NULL);
-	RCU_INIT_POINTER(mvm_sta->link[link_id], NULL);
-
-	if (mvm_sta_link != &mvm_sta->deflink)
-		kfree_rcu(mvm_sta_link, rcu_head);
-}
-
 static int iwl_mvm_mld_alloc_sta_link(struct iwl_mvm *mvm,
 				      struct ieee80211_vif *vif,
 				      struct ieee80211_sta *sta,
@@ -787,20 +784,24 @@ int iwl_mvm_mld_rm_sta(struct iwl_mvm *mvm, struct ieee80211_vif *vif,
 		struct iwl_mvm_link_sta *mvm_link_sta =
 			rcu_dereference_protected(mvm_sta->link[link_id],
 						  lockdep_is_held(&mvm->mutex));
+		bool stay_in_fw;
 
-		if (iwl_mvm_sta_del(mvm, vif, sta, mvm_link_sta, &ret))
-			return ret;
+		stay_in_fw = iwl_mvm_sta_del(mvm, vif, sta, mvm_link_sta, &ret);
+		if (ret)
+			break;
 
-		ret = iwl_mvm_mld_rm_sta_from_fw(mvm, mvm_link_sta->sta_id);
-	}
+		if (!stay_in_fw)
+			ret = iwl_mvm_mld_rm_sta_from_fw(mvm,
+							 mvm_link_sta->sta_id);
 
-	iwl_mvm_mld_sta_rm_all_sta_links(mvm, mvm_sta);
+		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, mvm_link_sta,
+					  link_id, stay_in_fw);
+	}
 
 	return ret;
 }
 
-int iwl_mvm_mld_rm_sta_id(struct iwl_mvm *mvm, struct ieee80211_vif *vif,
-			  u8 sta_id)
+int iwl_mvm_mld_rm_sta_id(struct iwl_mvm *mvm, u8 sta_id)
 {
 	int ret = iwl_mvm_mld_rm_sta_from_fw(mvm, sta_id);
 
@@ -978,7 +979,8 @@ int iwl_mvm_mld_update_sta_links(struct iwl_mvm *mvm,
 		if (vif->type == NL80211_IFTYPE_STATION)
 			mvm_vif_link->ap_sta_id = IWL_MVM_INVALID_STA;
 
-		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, mvm_sta_link, link_id);
+		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, mvm_sta_link, link_id,
+					  false);
 	}
 
 	for_each_set_bit(link_id, &links_to_add, IEEE80211_MLD_MAX_NUM_LINKS) {
@@ -1054,7 +1056,8 @@ int iwl_mvm_mld_update_sta_links(struct iwl_mvm *mvm,
 			rcu_dereference_protected(mvm_sta->link[link_id],
 						  lockdep_is_held(&mvm->mutex));
 
-		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, mvm_sta_link, link_id);
+		iwl_mvm_mld_free_sta_link(mvm, mvm_sta, mvm_sta_link, link_id,
+					  false);
 	}
 
 	return ret;

drivers/net/wireless/intel/iwlwifi/mvm/sta.h

@@ -639,8 +639,7 @@ int iwl_mvm_mld_update_sta(struct iwl_mvm *mvm, struct ieee80211_vif *vif,
 			   struct ieee80211_sta *sta);
 int iwl_mvm_mld_rm_sta(struct iwl_mvm *mvm, struct ieee80211_vif *vif,
 		       struct ieee80211_sta *sta);
-int iwl_mvm_mld_rm_sta_id(struct iwl_mvm *mvm, struct ieee80211_vif *vif,
-			  u8 sta_id);
+int iwl_mvm_mld_rm_sta_id(struct iwl_mvm *mvm, u8 sta_id);
 int iwl_mvm_mld_update_sta_links(struct iwl_mvm *mvm,
 				 struct ieee80211_vif *vif,
 				 struct ieee80211_sta *sta,