| 1 | /*
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| 2 | * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the Apache License 2.0 (the "License");
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| 5 | * you may not use this file except in compliance with the License.
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| 6 | * You may obtain a copy of the License at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | * or in the file LICENSE in the source distribution.
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| 9 | */
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| 10 |
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| 11 | /*
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| 12 | * Confirm that if (d, r) = a / b, then b * d + r == a, and that sign(d) ==
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| 13 | * sign(a), and 0 <= r <= b
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| 14 | */
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| 15 |
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| 16 | #include <stdio.h>
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| 17 | #include <openssl/bn.h>
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| 18 | #include <openssl/err.h>
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| 19 | #include "fuzzer.h"
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| 20 |
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| 21 | /* 256 kB */
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| 22 | #define MAX_LEN (256 * 1000)
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| 23 |
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| 24 | static BN_CTX *ctx;
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| 25 | static BIGNUM *b1;
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| 26 | static BIGNUM *b2;
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| 27 | static BIGNUM *b3;
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| 28 | static BIGNUM *b4;
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| 29 | static BIGNUM *b5;
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| 30 |
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| 31 | int FuzzerInitialize(int *argc, char ***argv)
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| 32 | {
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| 33 | b1 = BN_new();
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| 34 | b2 = BN_new();
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| 35 | b3 = BN_new();
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| 36 | b4 = BN_new();
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| 37 | b5 = BN_new();
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| 38 | ctx = BN_CTX_new();
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| 39 |
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| 40 | OPENSSL_init_crypto(OPENSSL_INIT_LOAD_CRYPTO_STRINGS, NULL);
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| 41 | ERR_clear_error();
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| 42 |
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| 43 | return 1;
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| 44 | }
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| 45 |
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| 46 | int FuzzerTestOneInput(const uint8_t *buf, size_t len)
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| 47 | {
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| 48 | int success = 0;
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| 49 | size_t l1 = 0, l2 = 0;
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| 50 | /* s1 and s2 will be the signs for b1 and b2. */
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| 51 | int s1 = 0, s2 = 0;
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| 52 |
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| 53 | /* limit the size of the input to avoid timeout */
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| 54 | if (len > MAX_LEN)
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| 55 | len = MAX_LEN;
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| 56 |
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| 57 | /* We are going to split the buffer in two, sizes l1 and l2, giving b1 and
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| 58 | * b2.
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| 59 | */
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| 60 | if (len > 0) {
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| 61 | --len;
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| 62 | /* Use first byte to divide the remaining buffer into 3Fths. I admit
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| 63 | * this disallows some number sizes. If it matters, better ideas are
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| 64 | * welcome (Ben).
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| 65 | */
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| 66 | l1 = ((buf[0] & 0x3f) * len) / 0x3f;
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| 67 | s1 = buf[0] & 0x40;
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| 68 | s2 = buf[0] & 0x80;
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| 69 | ++buf;
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| 70 | l2 = len - l1;
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| 71 | }
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| 72 | OPENSSL_assert(BN_bin2bn(buf, l1, b1) == b1);
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| 73 | BN_set_negative(b1, s1);
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| 74 | OPENSSL_assert(BN_bin2bn(buf + l1, l2, b2) == b2);
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| 75 | BN_set_negative(b2, s2);
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| 76 |
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| 77 | /* divide by 0 is an error */
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| 78 | if (BN_is_zero(b2)) {
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| 79 | success = 1;
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| 80 | goto done;
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| 81 | }
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| 82 |
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| 83 | OPENSSL_assert(BN_div(b3, b4, b1, b2, ctx));
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| 84 | if (BN_is_zero(b1))
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| 85 | success = BN_is_zero(b3) && BN_is_zero(b4);
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| 86 | else if (BN_is_negative(b1))
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| 87 | success = (BN_is_negative(b3) != BN_is_negative(b2) || BN_is_zero(b3))
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| 88 | && (BN_is_negative(b4) || BN_is_zero(b4));
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| 89 | else
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| 90 | success = (BN_is_negative(b3) == BN_is_negative(b2) || BN_is_zero(b3))
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| 91 | && (!BN_is_negative(b4) || BN_is_zero(b4));
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| 92 | OPENSSL_assert(BN_mul(b5, b3, b2, ctx));
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| 93 | OPENSSL_assert(BN_add(b5, b5, b4));
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| 94 |
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| 95 | success = success && BN_cmp(b5, b1) == 0;
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| 96 | if (!success) {
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| 97 | BN_print_fp(stdout, b1);
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| 98 | putchar('\n');
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| 99 | BN_print_fp(stdout, b2);
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| 100 | putchar('\n');
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| 101 | BN_print_fp(stdout, b3);
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| 102 | putchar('\n');
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| 103 | BN_print_fp(stdout, b4);
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| 104 | putchar('\n');
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| 105 | BN_print_fp(stdout, b5);
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| 106 | putchar('\n');
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| 107 | printf("%d %d %d %d %d %d %d\n", BN_is_negative(b1),
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| 108 | BN_is_negative(b2),
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| 109 | BN_is_negative(b3), BN_is_negative(b4), BN_is_zero(b4),
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| 110 | BN_is_negative(b3) != BN_is_negative(b2)
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| 111 | && (BN_is_negative(b4) || BN_is_zero(b4)),
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| 112 | BN_cmp(b5, b1));
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| 113 | puts("----\n");
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| 114 | }
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| 115 |
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| 116 | done:
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| 117 | OPENSSL_assert(success);
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| 118 | ERR_clear_error();
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| 119 |
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| 120 | return 0;
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| 121 | }
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| 122 |
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| 123 | void FuzzerCleanup(void)
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| 124 | {
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| 125 | BN_free(b1);
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| 126 | BN_free(b2);
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| 127 | BN_free(b3);
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| 128 | BN_free(b4);
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| 129 | BN_free(b5);
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| 130 | BN_CTX_free(ctx);
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| 131 | }
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