bpf: Skip oracle for subprogs

Signed-off-by: Paul Chaignon <[email protected]>

Author: pchaigno

kernel/bpf/oracle.c

@@ -35,6 +35,10 @@ int save_state_in_oracle(struct bpf_verifier_env *env, int insn_idx)
 	struct bpf_insn_aux_data *aux = cur_aux(env);
 	struct bpf_oracle_state_list *new_sl;
 
+	if (env->subprog_cnt > 1)
+		/* Skip the oracle if subprogs are used. */
+		return 0;
+
 	if (!aux->oracle_states) {
 		aux->oracle_states = kmalloc(sizeof(struct list_head), GFP_KERNEL_ACCOUNT);
 		if (!aux->oracle_states)
@@ -144,11 +148,14 @@ struct bpf_prog *patch_oracle_check_insn(struct bpf_verifier_env *env, struct bp
 	struct bpf_insn_aux_data *aux = &env->insn_aux_data[i];
 	struct list_head *head = aux->oracle_states;
 	struct bpf_insn *insn_buf = env->insn_buf;
-	struct bpf_prog *new_prog;
+	struct bpf_prog *new_prog = env->prog;
+	if (env->subprog_cnt > 1)
+		/* Skip the oracle if subprogs are used. */
+		goto noop;
 	int num_oracle_states = list_count_nodes(head);
 	int err;
 	if (!num_oracle_states)
-		return NULL;
+		goto noop;
 	struct bpf_map *inner_map = create_inner_oracle_map(num_oracle_states);
 	if (IS_ERR(inner_map))
 		return (void *)inner_map;
@@ -179,6 +186,10 @@ struct bpf_prog *patch_oracle_check_insn(struct bpf_verifier_env *env, struct bp
 		return ERR_PTR(err);
 
 	return new_prog;
+
+noop:
+	*cnt = 1;
+	return new_prog;
 }
 
 int populate_oracle_map(struct bpf_verifier_env *env, struct bpf_map *oracle_map)
@@ -238,7 +249,8 @@ struct bpf_map *create_oracle_map(struct bpf_verifier_env *env)
 	struct bpf_map *map = NULL, *inner_map;
 	int err;
 
-	if (env->num_prune_points == 0)
+	if (env->num_prune_points == 0 || env->subprog_cnt > 1)
+		/* Skip the oracle if subprogs are used. */
 		return map;
 
 	union bpf_attr map_attr = {

kernel/bpf/verifier.c

@@ -22645,8 +22645,6 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 	for (i = 0; i < insn_cnt;) {
 		if (is_prune_point(env, i + delta)) {
 			new_prog = patch_oracle_check_insn(env, insn, i + delta, &cnt);
-			if (!new_prog)
-				continue;
 			if (IS_ERR(new_prog))
 				return PTR_ERR(new_prog);