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-rw-r--r--security/nss/fuzz/mpi_expmod_target.cc36
1 files changed, 36 insertions, 0 deletions
diff --git a/security/nss/fuzz/mpi_expmod_target.cc b/security/nss/fuzz/mpi_expmod_target.cc
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/*
+ * This target fuzzes NSS mpi against openssl bignum.
+ * It therefore requires openssl to be installed.
+ */
+
+#include "mpi_helper.h"
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+ // We require at least size 3 to get two integers from Data.
+ if (size < 3) {
+ return 0;
+ }
+ INIT_FOUR_NUMBERS
+
+ auto modulus = get_modulus(data, size, ctx);
+ // Compare with OpenSSL exp mod
+ m1 = &std::get<1>(modulus);
+ // The exponent b (B) can get really big. Make it smaller if necessary.
+ if (MP_USED(&b) > 100) {
+ size_t shift = (MP_USED(&b) - 100) * MP_DIGIT_BIT;
+ mp_div_2d(&b, shift, &b, nullptr);
+ BN_rshift(B, B, shift);
+ }
+ check_equal(A, &a, max_size);
+ check_equal(B, &b, max_size);
+ check_equal(std::get<0>(modulus), m1, 3 * max_size);
+ assert(mp_exptmod(&a, &b, m1, &c) == MP_OKAY);
+ (void)BN_mod_exp(C, A, B, std::get<0>(modulus), ctx);
+ check_equal(C, &c, 2 * max_size);
+
+ CLEANUP_AND_RETURN
+}