Merge #18155: tests: Add harness which fuzzes EvalScript and VerifyScript using a fuzzed signature checker

5e47b19e50cf5a8de77dfe363988522cfd212c06 tests: Add harness which fuzzes EvalScript and VerifyScript using a fuzzed signature checker (practicalswift)

Pull request description:

  Add harness which fuzzes `EvalScript` and `VerifyScript` using a fuzzed signature checker.

  Test this PR using:

  ```
  $ make distclean
  $ ./autogen.sh
  $ CC=clang CXX=clang++ ./configure --enable-fuzz \
        --with-sanitizers=address,fuzzer,undefined
  $ make
  $ src/test/fuzz/signature_checker
  …
  ```

  Closes #17986.

Top commit has no ACKs.

Tree-SHA512: a9988f8fa7919fe470756ca3e4e75764a589f590769aab452c8f4c254cf41667793e52131d470a12629ec3681fa7fc20091f371b8f3e3eec105674c2769e7d7e

1 files changed, 68 insertions, 0 deletions

diff --git a/src/test/fuzz/signature_checker.cpp b/src/test/fuzz/signature_checker.cpp
new file mode 100644
index 0000000000..312db27adc
--- /dev/null
+++ b/src/test/fuzz/signature_checker.cpp
@@ -0,0 +1,68 @@
+// Copyright (c) 2009-2019 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 <pubkey.h>
+#include <script/interpreter.h>
+#include <test/fuzz/FuzzedDataProvider.h>
+#include <test/fuzz/fuzz.h>
+#include <util/memory.h>
+
+#include <cstdint>
+#include <limits>
+#include <string>
+#include <vector>
+
+void initialize()
+{
+    static const auto verify_handle = MakeUnique<ECCVerifyHandle>();
+}
+
+namespace {
+class FuzzedSignatureChecker : public BaseSignatureChecker
+{
+    FuzzedDataProvider& m_fuzzed_data_provider;
+
+public:
+    FuzzedSignatureChecker(FuzzedDataProvider& fuzzed_data_provider) : m_fuzzed_data_provider(fuzzed_data_provider)
+    {
+    }
+
+    virtual bool CheckSig(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
+    {
+        return m_fuzzed_data_provider.ConsumeBool();
+    }
+
+    virtual bool CheckLockTime(const CScriptNum& nLockTime) const
+    {
+        return m_fuzzed_data_provider.ConsumeBool();
+    }
+
+    virtual bool CheckSequence(const CScriptNum& nSequence) const
+    {
+        return m_fuzzed_data_provider.ConsumeBool();
+    }
+
+    virtual ~FuzzedSignatureChecker() {}
+};
+} // namespace
+
+void test_one_input(const std::vector<uint8_t>& buffer)
+{
+    FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    const unsigned int flags = fuzzed_data_provider.ConsumeIntegral<unsigned int>();
+    const SigVersion sig_version = fuzzed_data_provider.PickValueInArray({SigVersion::BASE, SigVersion::WITNESS_V0});
+    const std::string script_string_1 = fuzzed_data_provider.ConsumeRandomLengthString(65536);
+    const std::vector<uint8_t> script_bytes_1{script_string_1.begin(), script_string_1.end()};
+    const std::string script_string_2 = fuzzed_data_provider.ConsumeRandomLengthString(65536);
+    const std::vector<uint8_t> script_bytes_2{script_string_2.begin(), script_string_2.end()};
+    std::vector<std::vector<unsigned char>> stack;
+    (void)EvalScript(stack, {script_bytes_1.begin(), script_bytes_1.end()}, flags, FuzzedSignatureChecker(fuzzed_data_provider), sig_version, nullptr);
+    if ((flags & SCRIPT_VERIFY_CLEANSTACK) != 0 && ((flags & SCRIPT_VERIFY_P2SH) == 0 || (flags & SCRIPT_VERIFY_WITNESS) == 0)) {
+        return;
+    }
+    if ((flags & SCRIPT_VERIFY_WITNESS) != 0 && (flags & SCRIPT_VERIFY_P2SH) == 0) {
+        return;
+    }
+    (void)VerifyScript({script_bytes_1.begin(), script_bytes_1.end()}, {script_bytes_2.begin(), script_bytes_2.end()}, nullptr, flags, FuzzedSignatureChecker(fuzzed_data_provider), nullptr);
+}