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Merge bitcoin/bitcoin#31486: fuzz: Abort when using global PRNG without re-seed

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fae63bf130 fuzz: Clarify that only SeedRandomStateForTest(SeedRand::ZEROS) is allowed (MarcoFalke)
fa18acb457 fuzz: Abort when using global PRNG without re-seed (MarcoFalke)
fa7809aeab fuzz: Add missing SeedRandomStateForTest(SeedRand::ZEROS) (MarcoFalke)

Pull request description:

  This is the first step toward improving fuzz stability and determinism (https://github.com/bitcoin/bitcoin/issues/29018).

  A fuzz target using the global test-only PRNG will now abort if the seed is re-used across fuzz inputs.

  Also, temporarily add `SeedRandomStateForTest(SeedRand::ZEROS)` to all affected fuzz targets. This may slow down the libfuzzer leak detector, but it will disable itself after some time, or it can be disabled explicitly with `-detect_leaks=0`.

  In a follow-up, each affected fuzz target can be stripped of the global random use and a local `RandomMixin` (or similar) can be added instead.

  (Can be tested by removing any one of the re-seed calls and observing a fuzz abort)

ACKs for top commit:
  hodlinator:
    ACK fae63bf130
  dergoegge:
    utACK fae63bf130
  marcofleon:
    Tested ACK fae63bf130

Tree-SHA512: 4a0db69af7f715408edf4f8b08b44f34ce12ee2c79d33b336ad19a6e6bd079c4ff7c971af0a3efa428213407c1171f4e2837ec6a2577086c2f94cd15618a0892
This commit is contained in:
Ryan Ofsky
2024-12-17 12:33:41 -05:00
parent a95a8ba3a3 fae63bf130
commit a60d5702fd
39 changed files with 131 additions and 7 deletions
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6
src/test/util/random.cpp
View File

@@ -12,6 +12,8 @@
#include <cstdlib>
#include <iostream>
std::atomic<bool> g_seeded_g_prng_zero{false};
extern void MakeRandDeterministicDANGEROUS(const uint256& seed) noexcept;
void SeedRandomStateForTest(SeedRand seedtype)
@@ -36,6 +38,10 @@ void SeedRandomStateForTest(SeedRand seedtype)
return GetRandHash();
}();
g_seeded_g_prng_zero = seedtype == SeedRand::ZEROS;
if constexpr (G_FUZZING) {
Assert(g_seeded_g_prng_zero); // Only SeedRandomStateForTest(SeedRand::ZEROS) is allowed in fuzz tests
}
const uint256& seed{seedtype == SeedRand::FIXED_SEED ? ctx_seed : uint256::ZERO};
LogInfo("Setting random seed for current tests to %s=%s\n", RANDOM_CTX_SEED, seed.GetHex());
MakeRandDeterministicDANGEROUS(seed);

4
src/test/util/random.h
View File

@@ -9,6 +9,7 @@
#include <random.h>
#include <uint256.h>
#include <atomic>
#include <cstdint>
enum class SeedRand {
@@ -27,6 +28,9 @@ enum class SeedRand {
/** Seed the global RNG state for testing and log the seed value. This affects all randomness, except GetStrongRandBytes(). */
void SeedRandomStateForTest(SeedRand seed);
extern std::atomic<bool> g_seeded_g_prng_zero;
extern std::atomic<bool> g_used_g_prng;
template <RandomNumberGenerator Rng>
inline CAmount RandMoney(Rng&& rng)
{

5
src/test/util/setup_common.cpp
View File

@@ -108,6 +108,9 @@ static void ExitFailure(std::string_view str_err)
BasicTestingSetup::BasicTestingSetup(const ChainType chainType, TestOpts opts)
: m_args{}
{
if constexpr (!G_FUZZING) {
SeedRandomForTest(SeedRand::FIXED_SEED);
}
m_node.shutdown_signal = &m_interrupt;
m_node.shutdown_request = [this]{ return m_interrupt(); };
m_node.args = &gArgs;
@@ -139,8 +142,6 @@ BasicTestingSetup::BasicTestingSetup(const ChainType chainType, TestOpts opts)
}
}
SeedRandomForTest(SeedRand::FIXED_SEED);
const std::string test_name{G_TEST_GET_FULL_NAME ? G_TEST_GET_FULL_NAME() : ""};
if (!m_node.args->IsArgSet("-testdatadir")) {
// To avoid colliding with a leftover prior datadir, and to allow