tests: Add fuzzing harness for functions taking floating-point types as input

src/Makefile.test.include

@@ -29,6 +29,7 @@ FUZZ_TARGETS = \
   test/fuzz/eval_script \
   test/fuzz/fee_rate_deserialize \
   test/fuzz/flat_file_pos_deserialize \
+  test/fuzz/float \
   test/fuzz/hex \
   test/fuzz/integer \
   test/fuzz/inv_deserialize \
@@ -387,6 +388,12 @@ test_fuzz_flat_file_pos_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_flat_file_pos_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_flat_file_pos_deserialize_SOURCES = $(FUZZ_SUITE) test/fuzz/deserialize.cpp
 
+test_fuzz_float_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_float_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_float_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_float_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_float_SOURCES = $(FUZZ_SUITE) test/fuzz/float.cpp
+
 test_fuzz_hex_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
 test_fuzz_hex_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
 test_fuzz_hex_LDADD = $(FUZZ_SUITE_LD_COMMON)

src/test/fuzz/float.cpp

@@ -0,0 +1,42 @@
+// Copyright (c) 2020 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#include <memusage.h>
+#include <serialize.h>
+#include <streams.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <version.h>
+
+#include <cassert>
+#include <cstdint>
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+
+    {
+        const double d = fuzzed_data_provider.ConsumeFloatingPoint<double>();
+        (void)memusage::DynamicUsage(d);
+        assert(ser_uint64_to_double(ser_double_to_uint64(d)) == d);
+
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+        stream << d;
+        double d_deserialized;
+        stream >> d_deserialized;
+        assert(d == d_deserialized);
+    }
+
+    {
+        const float f = fuzzed_data_provider.ConsumeFloatingPoint<float>();
+        (void)memusage::DynamicUsage(f);
+        assert(ser_uint32_to_float(ser_float_to_uint32(f)) == f);
+
+        CDataStream stream(SER_NETWORK, INIT_PROTO_VERSION);
+        stream << f;
+        float f_deserialized;
+        stream >> f_deserialized;
+        assert(f == f_deserialized);
+    }
+}