Merge tag 'batadv-net-pullrequest-20241210' of git://git.open-mesh.org/linux-merge

Simon Wunderlich says:

====================
Here are some batman-adv bugfixes:

 - fix TT unitialized data and size limit issues, by Remi Pommarel
  (3 patches)

* tag 'batadv-net-pullrequest-20241210' of git://git.open-mesh.org/linux-merge:
  batman-adv: Do not let TT changes list grows indefinitely
  batman-adv: Remove uninitialized data in full table TT response
  batman-adv: Do not send uninitialized TT changes
====================

Link: https://patch.msgid.link/20241210135024.39068-1-sw@simonwunderlich.de
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

net/batman-adv/translation-table.c

@@ -948,16 +948,25 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
 	int tt_diff_len, tt_change_len = 0;
 	int tt_diff_entries_num = 0;
 	int tt_diff_entries_count = 0;
+	bool drop_changes = false;
+	size_t tt_extra_len = 0;
 	u16 tvlv_len;
 
 	tt_diff_entries_num = atomic_read(&bat_priv->tt.local_changes);
 	tt_diff_len = batadv_tt_len(tt_diff_entries_num);
 
 	/* if we have too many changes for one packet don't send any
-	 * and wait for the tt table request which will be fragmented
+	 * and wait for the tt table request so we can reply with the full
+	 * (fragmented) table.
+	 *
+	 * The local change history should still be cleaned up so the next
+	 * TT round can start again with a clean state.
 	 */
-	if (tt_diff_len > bat_priv->soft_iface->mtu)
+	if (tt_diff_len > bat_priv->soft_iface->mtu) {
 		tt_diff_len = 0;
+		tt_diff_entries_num = 0;
+		drop_changes = true;
+	}
 
 	tvlv_len = batadv_tt_prepare_tvlv_local_data(bat_priv, &tt_data,
 						     &tt_change, &tt_diff_len);
@@ -966,7 +975,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
 
 	tt_data->flags = BATADV_TT_OGM_DIFF;
 
-	if (tt_diff_len == 0)
+	if (!drop_changes && tt_diff_len == 0)
 		goto container_register;
 
 	spin_lock_bh(&bat_priv->tt.changes_list_lock);
@@ -985,6 +994,9 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
 	}
 	spin_unlock_bh(&bat_priv->tt.changes_list_lock);
 
+	tt_extra_len = batadv_tt_len(tt_diff_entries_num -
+				     tt_diff_entries_count);
+
 	/* Keep the buffer for possible tt_request */
 	spin_lock_bh(&bat_priv->tt.last_changeset_lock);
 	kfree(bat_priv->tt.last_changeset);
@@ -993,6 +1005,7 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
 	tt_change_len = batadv_tt_len(tt_diff_entries_count);
 	/* check whether this new OGM has no changes due to size problems */
 	if (tt_diff_entries_count > 0) {
+		tt_diff_len -= tt_extra_len;
 		/* if kmalloc() fails we will reply with the full table
 		 * instead of providing the diff
 		 */
@@ -1005,6 +1018,8 @@ static void batadv_tt_tvlv_container_update(struct batadv_priv *bat_priv)
 	}
 	spin_unlock_bh(&bat_priv->tt.last_changeset_lock);
 
+	/* Remove extra packet space for OGM */
+	tvlv_len -= tt_extra_len;
 container_register:
 	batadv_tvlv_container_register(bat_priv, BATADV_TVLV_TT, 1, tt_data,
 				       tvlv_len);
@@ -2705,14 +2720,16 @@ static bool batadv_tt_global_valid(const void *entry_ptr,
  *
  * Fills the tvlv buff with the tt entries from the specified hash. If valid_cb
  * is not provided then this becomes a no-op.
+ *
+ * Return: Remaining unused length in tvlv_buff.
  */
-static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
-				    struct batadv_hashtable *hash,
-				    void *tvlv_buff, u16 tt_len,
-				    bool (*valid_cb)(const void *,
-						     const void *,
-						     u8 *flags),
-				    void *cb_data)
+static u16 batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
+				   struct batadv_hashtable *hash,
+				   void *tvlv_buff, u16 tt_len,
+				   bool (*valid_cb)(const void *,
+						    const void *,
+						    u8 *flags),
+				   void *cb_data)
 {
 	struct batadv_tt_common_entry *tt_common_entry;
 	struct batadv_tvlv_tt_change *tt_change;
@@ -2726,7 +2743,7 @@ static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
 	tt_change = tvlv_buff;
 
 	if (!valid_cb)
-		return;
+		return tt_len;
 
 	rcu_read_lock();
 	for (i = 0; i < hash->size; i++) {
@@ -2752,6 +2769,8 @@ static void batadv_tt_tvlv_generate(struct batadv_priv *bat_priv,
 		}
 	}
 	rcu_read_unlock();
+
+	return batadv_tt_len(tt_tot - tt_num_entries);
 }
 
 /**
@@ -3022,10 +3041,11 @@ static bool batadv_send_other_tt_response(struct batadv_priv *bat_priv,
 			goto out;
 
 		/* fill the rest of the tvlv with the real TT entries */
-		batadv_tt_tvlv_generate(bat_priv, bat_priv->tt.global_hash,
-					tt_change, tt_len,
-					batadv_tt_global_valid,
-					req_dst_orig_node);
+		tvlv_len -= batadv_tt_tvlv_generate(bat_priv,
+						    bat_priv->tt.global_hash,
+						    tt_change, tt_len,
+						    batadv_tt_global_valid,
+						    req_dst_orig_node);
 	}
 
 	/* Don't send the response, if larger than fragmented packet. */
@@ -3149,9 +3169,11 @@ static bool batadv_send_my_tt_response(struct batadv_priv *bat_priv,
 			goto out;
 
 		/* fill the rest of the tvlv with the real TT entries */
-		batadv_tt_tvlv_generate(bat_priv, bat_priv->tt.local_hash,
-					tt_change, tt_len,
-					batadv_tt_local_valid, NULL);
+		tvlv_len -= batadv_tt_tvlv_generate(bat_priv,
+						    bat_priv->tt.local_hash,
+						    tt_change, tt_len,
+						    batadv_tt_local_valid,
+						    NULL);
 	}
 
 	tvlv_tt_data->flags = BATADV_TT_RESPONSE;