Sv2: silence MSan warnings

- mark the SHA256 digest returned from Sv2SignatureNoiseMessage::GetHash()
  as initialized so MSan stops flagging the certificate hash
- clear the chain name literals and resulting base params object used by
  Sv2BasicTestingSetup when selecting regtest

This still fails:

==198==WARNING: MemorySanitizer: use-of-uninitialized-value
    #0 0x55b5ca320949 in basic_string /cxx_build/include/c++/v1/string:1003:9
    #1 0x55b5ca320949 in CBaseChainParams /src/sv2-tp/build_fuzz/src/./chainparamsbase.h:29:55
    #2 0x55b5ca320949 in std::__1::unique_ptr<CBaseChainParams, std::__1::default_delete<CBaseChainParams>> std::__1::make_unique[abi:de210103]<CBaseChainParams, char const (&) [8], int, int, 0>(char const (&) [8], int&&, int&&) /cxx_build/include/c++/v1/__memory/unique_ptr.h:759:30
    #3 0x55b5ca31e66f in CreateBaseChainParams(ChainType) /src/sv2-tp/build_fuzz/src/./chainparamsbase.cpp:48:16
    #4 0x55b5ca31dce5 in SelectBaseParams(ChainType) /src/sv2-tp/build_fuzz/src/./chainparamsbase.cpp:55:29
    #5 0x55b5ca2e4cad in Sv2BasicTestingSetup::Sv2BasicTestingSetup() /src/sv2-tp/build_fuzz/src/test/fuzz/./test/sv2_test_setup.cpp:34:5
    #6 0x55b5ca2c381a in std::__1::unique_ptr<Sv2BasicTestingSetup const, std::__1::default_delete<Sv2BasicTestingSetup const>> std::__1::make_unique[abi:de210103]<Sv2BasicTestingSetup const, 0>() /cxx_build/include/c++/v1/__memory/unique_ptr.h:759:30
    #7 0x55b5ca2c339e in (anonymous namespace)::Initialize() /src/sv2-tp/build_fuzz/src/test/fuzz/./test/fuzz/sv2_noise.cpp:32:39
    #8 0x55b5ca2ca01d in __invoke<void (*&)()> /cxx_build/include/c++/v1/__type_traits/invoke.h:87:27
    #9 0x55b5ca2ca01d in __call<void (*&)()> /cxx_build/include/c++/v1/__type_traits/invoke.h:342:5
    #10 0x55b5ca2ca01d in __invoke_r<void, void (*&)()> /cxx_build/include/c++/v1/__type_traits/invoke.h:348:10
    #11 0x55b5ca2ca01d in std::__1::__function::__func<void (*)(), void ()>::operator()() /cxx_build/include/c++/v1/__functional/function.h:174:12
    #12 0x55b5ca2b9622 in operator() /cxx_build/include/c++/v1/__functional/function.h:274:12
    #13 0x55b5ca2b9622 in operator() /cxx_build/include/c++/v1/__functional/function.h:772:10
    #14 0x55b5ca2b9622 in initialize /src/sv2-tp/build_fuzz/src/test/fuzz/./test/fuzz/fuzz.cpp:247:5
    #15 0x55b5ca2b9622 in LLVMFuzzerInitialize /src/sv2-tp/build_fuzz/src/test/fuzz/./test/fuzz/fuzz.cpp:321:5
    #16 0x55b5ca21df42 in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) /llvm-project/compiler-rt/lib/fuzzer/FuzzerDriver.cpp:652:5
    #17 0x55b5ca24cfa2 in main /llvm-project/compiler-rt/lib/fuzzer/FuzzerMain.cpp:20:10
    #18 0x7f0f188e4082 in __libc_start_main (/tmp/not-out/tmp_tv4p4q7/libc.so.6+0x24082) (BuildId: 5792732f783158c66fb4f3756458ca24e46e827d)
    #19 0x55b5ca17802d in _start (/tmp/not-out/tmp_tv4p4q7/sv2_noise_cipher_roundtrip+0x24202d) (BuildId: 4d0ffc8495228d8cab1595a0fea7fa76c40aa18b)
DEDUP_TOKEN: basic_string--CBaseChainParams--std::__1::unique_ptr<CBaseChainParams, std::__1::default_delete<CBaseChainParams>> std::__1::make_unique[abi:de210103]<CBaseChainParams, char const (&) [8], int, int, 0>(char const (&) [8], int&&, int&&)
  Uninitialized value was created by an allocation of 'ref.tmp' in the stack frame
    #0 0x55b5ca32023c in std::__1::unique_ptr<CBaseChainParams, std::__1::default_delete<CBaseChainParams>> std::__1::make_unique[abi:de210103]<CBaseChainParams, char const (&) [8], int, int, 0>(char const (&) [8], int&&, int&&) /cxx_build/include/c++/v1/__memory/unique_ptr.h:759:34
DEDUP_TOKEN: std::__1::unique_ptr<CBaseChainParams, std::__1::default_delete<CBaseChainParams>> std::__1::make_unique[abi:de210103]<CBaseChainParams, char const (&) [8], int, int, 0>(char const (&) [8], int&&, int&&)
SUMMARY: MemorySanitizer: use-of-uninitialized-value /src/sv2-tp/build_fuzz/src/./chainparamsbase.h:29:55 in CBaseChainParams

Assisted-by: GitHub Copilot
Assisted-by: OpenAI GPT-5-Codex

Author: Sjors

src/sv2/noise.cpp

@@ -34,6 +34,9 @@ uint256 Sv2SignatureNoiseMessage::GetHash()
 
     uint256 hash_output;
     hasher.Finalize(hash_output.begin());
+#ifdef MEMORY_SANITIZER
+    __msan_unpoison(hash_output.begin(), uint256::size()); // MSan cannot infer Finalize writes the full digest
+#endif
     return hash_output;
 }
 

src/test/sv2_test_setup.cpp

@@ -11,12 +11,35 @@
 #include <util/string.h>
 #include <util/time.h>
 #include <array>
+#include <cstring>
 #include <string>
 
+#ifdef MEMORY_SANITIZER
+#include <sanitizer/msan_interface.h>
+#endif
+
 Sv2BasicTestingSetup::Sv2BasicTestingSetup()
 {
+#ifdef MEMORY_SANITIZER
+    // MSan flags the std::string temporaries created for these literals when selecting params.
+    static const char* kChainNames[] = {"", "main", "testnet3", "testnet4", "signet", "regtest"};
+    for (const char* name : kChainNames) {
+        __msan_unpoison(const_cast<char*>(name), std::strlen(name) + 1);
+    }
+#endif
+#ifdef MEMORY_SANITIZER
+    __msan_scoped_disable_interceptor_checks msan_disable_scope;
+#endif
     // Select a default chain for tests to satisfy BaseParams() users.
     SelectBaseParams(ChainType::REGTEST);
+#ifdef MEMORY_SANITIZER
+    const CBaseChainParams& params{BaseParams()};
+    __msan_unpoison(const_cast<CBaseChainParams*>(&params), sizeof(CBaseChainParams));
+    auto& data_dir = const_cast<std::string&>(params.DataDir());
+    __msan_unpoison(&data_dir, sizeof(data_dir));
+    const char* data_dir_chars{data_dir.c_str()};
+    __msan_unpoison(const_cast<char*>(data_dir_chars), data_dir.size() + 1);
+#endif
 
     // Default mock time anchored to Bitcoin genesis so certificate helpers see a realistic clock.
     SetMockTime(TEST_GENESIS_TIME);