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author | Pauli <pauli@openssl.org> | 2021-07-05 11:01:59 +1000 |
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committer | Pauli <pauli@openssl.org> | 2021-07-07 19:12:48 +1000 |
commit | 105c83150f15af3f78ea0758859062842bdbe30e (patch) | |
tree | 2c1e1ea773116bea76651a767c1b478825997114 /test/bntest.c | |
parent | 0f71b1eb6c390e58059a4c4225bcbecac9aef2c7 (diff) | |
download | openssl-105c83150f15af3f78ea0758859062842bdbe30e.zip openssl-105c83150f15af3f78ea0758859062842bdbe30e.tar.gz openssl-105c83150f15af3f78ea0758859062842bdbe30e.tar.bz2 |
bn: procduce correct sign for result of BN_mod()
There is a problem that appears when calling BN_div(a, c, a, b) with negative b.
In this case, the sign of the remainder c is incorrect. The problem only
occurs if the dividend and the quotient are the same BIGNUM.
Fixes #15982
Reviewed-by: Nicola Tuveri <nic.tuv@gmail.com>
(Merged from https://github.com/openssl/openssl/pull/15991)
Diffstat (limited to 'test/bntest.c')
-rw-r--r-- | test/bntest.c | 77 |
1 files changed, 75 insertions, 2 deletions
diff --git a/test/bntest.c b/test/bntest.c index 5bbef1f..86fa163 100644 --- a/test/bntest.c +++ b/test/bntest.c @@ -308,6 +308,75 @@ static int test_div_recip(void) return st; } +static struct { + int n, divisor, result, remainder; +} signed_mod_tests[] = { + { 10, 3, 3, 1 }, + { -10, 3, -3, -1 }, + { 10, -3, -3, 1 }, + { -10, -3, 3, -1 }, +}; + +static BIGNUM *set_signed_bn(int value) +{ + BIGNUM *bn = BN_new(); + + if (bn == NULL) + return NULL; + if (!BN_set_word(bn, value < 0 ? -value : value)) { + BN_free(bn); + return NULL; + } + BN_set_negative(bn, value < 0); + return bn; +} + +static int test_signed_mod_replace_ab(int n) +{ + BIGNUM *a = NULL, *b = NULL, *c = NULL, *d = NULL; + int st = 0; + + if (!TEST_ptr(a = set_signed_bn(signed_mod_tests[n].n)) + || !TEST_ptr(b = set_signed_bn(signed_mod_tests[n].divisor)) + || !TEST_ptr(c = set_signed_bn(signed_mod_tests[n].result)) + || !TEST_ptr(d = set_signed_bn(signed_mod_tests[n].remainder))) + goto err; + + if (TEST_true(BN_div(a, b, a, b, ctx)) + && TEST_BN_eq(a, c) + && TEST_BN_eq(b, d)) + st = 1; + err: + BN_free(a); + BN_free(b); + BN_free(c); + BN_free(d); + return st; +} + +static int test_signed_mod_replace_ba(int n) +{ + BIGNUM *a = NULL, *b = NULL, *c = NULL, *d = NULL; + int st = 0; + + if (!TEST_ptr(a = set_signed_bn(signed_mod_tests[n].n)) + || !TEST_ptr(b = set_signed_bn(signed_mod_tests[n].divisor)) + || !TEST_ptr(c = set_signed_bn(signed_mod_tests[n].result)) + || !TEST_ptr(d = set_signed_bn(signed_mod_tests[n].remainder))) + goto err; + + if (TEST_true(BN_div(b, a, a, b, ctx)) + && TEST_BN_eq(b, c) + && TEST_BN_eq(a, d)) + st = 1; + err: + BN_free(a); + BN_free(b); + BN_free(c); + BN_free(d); + return st; +} + static int test_mod(void) { BIGNUM *a = NULL, *b = NULL, *c = NULL, *d = NULL, *e = NULL; @@ -329,8 +398,10 @@ static int test_mod(void) BN_set_negative(b, rand_neg()); if (!(TEST_true(BN_mod(c, a, b, ctx)) && TEST_true(BN_div(d, e, a, b, ctx)) - && TEST_true(BN_sub(e, e, c)) - && TEST_BN_eq_zero(e))) + && TEST_BN_eq(e, c) + && TEST_true(BN_mul(c, d, b, ctx)) + && TEST_true(BN_add(d, c, e)) + && TEST_BN_eq(d, a))) goto err; } st = 1; @@ -2875,6 +2946,8 @@ int setup_tests(void) if (n == 0) { ADD_TEST(test_sub); ADD_TEST(test_div_recip); + ADD_ALL_TESTS(test_signed_mod_replace_ab, OSSL_NELEM(signed_mod_tests)); + ADD_ALL_TESTS(test_signed_mod_replace_ba, OSSL_NELEM(signed_mod_tests)); ADD_TEST(test_mod); ADD_TEST(test_modexp_mont5); ADD_TEST(test_kronecker); |