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/*
* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* https://www.openssl.org/source/license.html
* or in the file LICENSE in the source distribution.
*/
/*
* Confirm that if (d, r) = a / b, then b * d + r == a, and that sign(d) ==
* sign(a), and 0 <= r <= b
*/
#include <stdio.h>
#include <openssl/bn.h>
#include <openssl/err.h>
#include "fuzzer.h"
/* 256 kB */
#define MAX_LEN (256 * 1000)
static BN_CTX *ctx;
static BIGNUM *b1;
static BIGNUM *b2;
static BIGNUM *b3;
static BIGNUM *b4;
static BIGNUM *b5;
int FuzzerInitialize(int *argc, char ***argv)
{
b1 = BN_new();
b2 = BN_new();
b3 = BN_new();
b4 = BN_new();
b5 = BN_new();
ctx = BN_CTX_new();
OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL);
ERR_clear_error();
return 1;
}
int FuzzerTestOneInput(const uint8_t *buf, size_t len)
{
int success = 0;
size_t l1 = 0, l2 = 0;
/* s1 and s2 will be the signs for b1 and b2. */
int s1 = 0, s2 = 0;
/* limit the size of the input to avoid timeout */
if (len > MAX_LEN)
len = MAX_LEN;
/* We are going to split the buffer in two, sizes l1 and l2, giving b1 and
* b2.
*/
if (len > 0) {
--len;
/* Use first byte to divide the remaining buffer into 3Fths. I admit
* this disallows some number sizes. If it matters, better ideas are
* welcome (Ben).
*/
l1 = ((buf[0] & 0x3f) * len) / 0x3f;
s1 = buf[0] & 0x40;
s2 = buf[0] & 0x80;
++buf;
l2 = len - l1;
}
OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
BN_set_negative(b1, s1);
OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
BN_set_negative(b2, s2);
/* divide by 0 is an error */
if (BN_is_zero(b2)) {
success = 1;
goto done;
}
OPENSSL_assert(BN_div(b3, b4, b1, b2, ctx));
if (BN_is_zero(b1))
success = BN_is_zero(b3) && BN_is_zero(b4);
else if (BN_is_negative(b1))
success = (BN_is_negative(b3) != BN_is_negative(b2) || BN_is_zero(b3))
&& (BN_is_negative(b4) || BN_is_zero(b4));
else
success = (BN_is_negative(b3) == BN_is_negative(b2) || BN_is_zero(b3))
&& (!BN_is_negative(b4) || BN_is_zero(b4));
OPENSSL_assert(BN_mul(b5, b3, b2, ctx));
OPENSSL_assert(BN_add(b5, b5, b4));
success = success && BN_cmp(b5, b1) == 0;
if (!success) {
BN_print_fp(stdout, b1);
putchar('\n');
BN_print_fp(stdout, b2);
putchar('\n');
BN_print_fp(stdout, b3);
putchar('\n');
BN_print_fp(stdout, b4);
putchar('\n');
BN_print_fp(stdout, b5);
putchar('\n');
printf("%d %d %d %d %d %d %d\n", BN_is_negative(b1),
BN_is_negative(b2),
BN_is_negative(b3), BN_is_negative(b4), BN_is_zero(b4),
BN_is_negative(b3) != BN_is_negative(b2)
&& (BN_is_negative(b4) || BN_is_zero(b4)),
BN_cmp(b5, b1));
puts("----\n");
}
done:
OPENSSL_assert(success);
ERR_clear_error();
return 0;
}
void FuzzerCleanup(void)
{
BN_free(b1);
BN_free(b2);
BN_free(b3);
BN_free(b4);
BN_free(b5);
BN_CTX_free(ctx);
}
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