netfilter: nf_tables: remove catchall element in GC sync path

cve CVE-2023-6111
commit-author Pablo Neira Ayuso <[email protected]>
commit 93995bf

The expired catchall element is not deactivated and removed from GC sync
path. This path holds mutex so just call nft_setelem_data_deactivate()
and nft_setelem_catchall_remove() before queueing the GC work.

Fixes: 4a9e12e ("netfilter: nft_set_pipapo: call nft_trans_gc_queue_sync() in catchall GC")
	Reported-by: lonial con <[email protected]>
	Signed-off-by: Pablo Neira Ayuso <[email protected]>
(cherry picked from commit 93995bf)
	Signed-off-by: Marcin Wcisło <[email protected]>

Author: pvts-mat

net/netfilter/nf_tables_api.c

@@ -6223,6 +6223,12 @@ static int nft_setelem_deactivate(const struct net *net,
 	return ret;
 }
 
+static void nft_setelem_catchall_destroy(struct nft_set_elem_catchall *catchall)
+{
+	list_del_rcu(&catchall->list);
+	kfree_rcu(catchall, rcu);
+}
+
 static void nft_setelem_catchall_remove(const struct net *net,
 					const struct nft_set *set,
 					const struct nft_set_elem *elem)
@@ -6231,8 +6237,7 @@ static void nft_setelem_catchall_remove(const struct net *net,
 
 	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
 		if (catchall->elem == elem->priv) {
-			list_del_rcu(&catchall->list);
-			kfree_rcu(catchall, rcu);
+			nft_setelem_catchall_destroy(catchall);
 			break;
 		}
 	}
@@ -9295,11 +9300,12 @@ static struct nft_trans_gc *nft_trans_gc_catchall(struct nft_trans_gc *gc,
 						  unsigned int gc_seq,
 						  bool sync)
 {
-	struct nft_set_elem_catchall *catchall;
+	struct nft_set_elem_catchall *catchall, *next;
 	const struct nft_set *set = gc->set;
+	struct nft_elem_priv *elem_priv;
 	struct nft_set_ext *ext;
 
-	list_for_each_entry_rcu(catchall, &set->catchall_list, list) {
+	list_for_each_entry_safe(catchall, next, &set->catchall_list, list) {
 		ext = nft_set_elem_ext(set, catchall->elem);
 
 		if (!nft_set_elem_expired(ext))
@@ -9317,7 +9323,17 @@ static struct nft_trans_gc *nft_trans_gc_catchall(struct nft_trans_gc *gc,
 		if (!gc)
 			return NULL;
 
-		nft_trans_gc_elem_add(gc, catchall->elem);
+		elem_priv = catchall->elem;
+		if (sync) {
+			struct nft_set_elem elem = {
+				.priv = elem_priv,
+			};
+
+			nft_setelem_data_deactivate(gc->net, gc->set, &elem);
+			nft_setelem_catchall_destroy(catchall);
+		}
+
+		nft_trans_gc_elem_add(gc, elem_priv);
 	}
 
 	return gc;