Coverage Report

Created: 2021-02-21 07:20

/src/botan/src/fuzzer/divide.cpp
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/*
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* (C) 2015,2016,2018 Jack Lloyd
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*
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* Botan is released under the Simplified BSD License (see license.txt)
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*/
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#include "fuzzers.h"
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#include <botan/internal/divide.h>
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void fuzz(const uint8_t in[], size_t len)
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   {
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   if(len % 2 == 1 || len > 2*4096/8)
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      return;
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   // Save on allocations by making these static
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   static Botan::BigInt x, y, q, r, ct_q, ct_r, z;
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   x = Botan::BigInt::decode(in, len / 2);
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   y = Botan::BigInt::decode(in + len / 2, len / 2);
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   if(y == 0)
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      return;
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   Botan::vartime_divide(x, y, q, r);
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   FUZZER_ASSERT_TRUE(r < y);
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   z = q*y + r;
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   FUZZER_ASSERT_EQUAL(z, x);
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   Botan::ct_divide(x, y, ct_q, ct_r);
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   FUZZER_ASSERT_EQUAL(q, ct_q);
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   FUZZER_ASSERT_EQUAL(r, ct_r);
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   // Now divide by just low byte of y
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   y = y.byte_at(0);
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   if(y == 0)
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      y = 251;
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   Botan::vartime_divide(x, y, q, r);
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   z = q*y + r;
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   FUZZER_ASSERT_EQUAL(z, x);
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   uint8_t r8;
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   Botan::ct_divide_u8(x, y.byte_at(0), ct_q, r8);
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   FUZZER_ASSERT_EQUAL(ct_q, q);
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   FUZZER_ASSERT_EQUAL(r8, r.byte_at(0));
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   }
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