fuzz/libtasn1_array2tree_fuzzer.c

/*
 * Copyright(c) 2019 Free Software Foundation, Inc.
 *
 * This file is part of libtasn1.
 *
 * Libtasn1 is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Libtasn1 is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with libtasn1.  If not, see <https://www.gnu.org/licenses/>.
 *
 * This fuzzer is testing asn1_array2tree()'s robustness with arbitrary
 * input data.
 */

#include <config.h>

#include <assert.h> // assert
#include <stdlib.h> // malloc, free
#include <string.h> // memcpy

#include "libtasn1.h"
#include "fuzzer.h"

const asn1_static_node pkix_asn1_tab[] = {
	{ "PKIX1Implicit88", 536875024, NULL },
	{ NULL, 0, NULL }
};

#define NAMESIZE  20
#define VALUESIZE 20
struct fuzz_elem {
	unsigned int type;
	char name[NAMESIZE];
	char value[VALUESIZE];
};

#define MAXELEM 100
#define MAXDATASIZE (100 * sizeof(struct fuzz_elem))

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size)
{
	if (size > MAXDATASIZE) // same as max_len = <MAXDATASIZE> in .options file
		return 0;

	struct fuzz_elem *elem = (struct fuzz_elem *) malloc(size);
	assert(elem != NULL);
	memcpy(elem, data, size);

	int nelem = size / sizeof(struct fuzz_elem);
	asn1_static_node tab[MAXELEM + 1]; // avoid VLA here

	for (int it = 0; it < nelem; it++) {
		tab[it].type = elem[it].type;
		elem[it].name[NAMESIZE - 1] = 0;
		if (strcmp(elem[it].name, "NULL"))
			tab[it].name = elem[it].name;
		else
			tab[it].name = NULL;
		elem[it].value[VALUESIZE -1] = 0;
		if (strcmp(elem[it].value, "NULL"))
			tab[it].value = elem[it].value;
		else
			tab[it].value = NULL;
	}

	// end-of-array indicator
	tab[nelem].type = 0;
	tab[nelem].name = NULL;
	tab[nelem].value = NULL;

	int result;
	asn1_node node = NULL;
	char errorDescription[ASN1_MAX_ERROR_DESCRIPTION_SIZE];

	result =
		asn1_array2tree(tab, &node, errorDescription);

	if (result == ASN1_SUCCESS)
		asn1_delete_structure(&node);

	free(elem);

	return 0;
}