tests: Add fuzzing harness for LoadMempool(...) and DumpMempool(...)

src/Makefile.test.include

@@ -139,7 +139,8 @@ FUZZ_TARGETS = \
   test/fuzz/txoutcompressor_deserialize \
   test/fuzz/txundo_deserialize \
   test/fuzz/uint160_deserialize \
-  test/fuzz/uint256_deserialize
+  test/fuzz/uint256_deserialize \
+  test/fuzz/validation_load_mempool
 
 if ENABLE_FUZZ
 noinst_PROGRAMS += $(FUZZ_TARGETS:=)
@@ -1130,6 +1131,12 @@ test_fuzz_uint256_deserialize_LDADD = $(FUZZ_SUITE_LD_COMMON)
 test_fuzz_uint256_deserialize_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
 test_fuzz_uint256_deserialize_SOURCES = test/fuzz/deserialize.cpp
 
+test_fuzz_validation_load_mempool_CPPFLAGS = $(AM_CPPFLAGS) $(BITCOIN_INCLUDES)
+test_fuzz_validation_load_mempool_CXXFLAGS = $(AM_CXXFLAGS) $(PIE_FLAGS)
+test_fuzz_validation_load_mempool_LDADD = $(FUZZ_SUITE_LD_COMMON)
+test_fuzz_validation_load_mempool_LDFLAGS = $(RELDFLAGS) $(AM_LDFLAGS) $(LIBTOOL_APP_LDFLAGS)
+test_fuzz_validation_load_mempool_SOURCES = test/fuzz/validation_load_mempool.cpp
+
 endif # ENABLE_FUZZ
 
 nodist_test_test_bitcoin_SOURCES = $(GENERATED_TEST_FILES)

src/test/fuzz/validation_load_mempool.cpp

@@ -0,0 +1,41 @@
+// 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 <chainparamsbase.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <test/fuzz/util.h>
+#include <test/util/setup_common.h>
+#include <txmempool.h>
+#include <validation.h>
+
+#include <cstdint>
+#include <vector>
+
+namespace {
+FuzzedFileProvider* fuzzed_file_provider_ptr = nullptr;
+
+FILE* fuzzed_fopen(const fs::path&, const char*)
+{
+    return fuzzed_file_provider_ptr->open();
+}
+} // namespace
+
+void initialize()
+{
+    static TestingSetup setup{CBaseChainParams::REGTEST, {"-nodebuglogfile"}};
+}
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider{buffer.data(), buffer.size()};
+    FuzzedFileProvider fuzzed_file_provider = ConsumeFile(fuzzed_data_provider);
+    fuzzed_file_provider_ptr = &fuzzed_file_provider;
+
+    CTxMemPool pool;
+    (void)LoadMempool(pool, fuzzed_fopen);
+    (void)DumpMempool(pool, fuzzed_fopen, true);
+
+    fuzzed_file_provider_ptr = nullptr;
+}