add asserts in CheckBlockIndex, remove BLOCK_FAILED_(CHILD|MASK) in fuzz test

- also modify block_index_tree.cpp to add blocks

Author: stratospher

src/test/fuzz/block_index_tree.cpp

@@ -39,6 +39,7 @@ void initialize_block_index_tree()
 FUZZ_TARGET(block_index_tree, .init = initialize_block_index_tree)
 {
     FuzzedDataProvider fuzzed_data_provider(buffer.data(), buffer.size());
+    SetMockTime(ConsumeTime(fuzzed_data_provider));
     ChainstateManager& chainman = *g_setup->m_node.chainman;
     auto& blockman = chainman.m_blockman;
     CBlockIndex* genesis = chainman.ActiveChainstate().m_chain[0];
@@ -54,18 +55,19 @@ FUZZ_TARGET(block_index_tree, .init = initialize_block_index_tree)
                 // Receive a header building on an existing one. This assumes headers are valid, so PoW is not relevant here.
                 LOCK(cs_main);
                 CBlockIndex* prev_block = PickValue(fuzzed_data_provider, blocks);
-                if (!(prev_block->nStatus & BLOCK_FAILED_MASK)) {
+                if (!(prev_block->nStatus & BLOCK_FAILED_VALID)) {
                     CBlockHeader header = ConsumeBlockHeader(fuzzed_data_provider, prev_block->GetBlockHash(), nonce_counter);
                     CBlockIndex* index = blockman.AddToBlockIndex(header, chainman.m_best_header);
                     assert(index->nStatus & BLOCK_VALID_TREE);
+                    blocks.push_back(index);
                 }
             },
             [&] {
                 // Receive a full block (valid or invalid) for an existing header, but don't attempt to connect it yet
                 LOCK(cs_main);
                 CBlockIndex* index = PickValue(fuzzed_data_provider, blocks);
                 // Must be new to us and not known to be invalid (e.g. because of an invalid ancestor).
-                if (index->nTx == 0 && !(index->nStatus & BLOCK_FAILED_MASK)) {
+                if (index->nTx == 0 && !(index->nStatus & BLOCK_FAILED_VALID)) {
                     if (fuzzed_data_provider.ConsumeBool()) { // Invalid
                         BlockValidationState state;
                         state.Invalid(BlockValidationResult::BLOCK_CONSENSUS, "consensus-invalid");
@@ -118,7 +120,7 @@ FUZZ_TARGET(block_index_tree, .init = initialize_block_index_tree)
                     }
                     // Connect blocks, possibly fail
                     for (CBlockIndex* block : to_connect | std::views::reverse) {
-                        assert(!(block->nStatus & BLOCK_FAILED_MASK));
+                        assert(!(block->nStatus & BLOCK_FAILED_VALID));
                         assert(block->nStatus & BLOCK_HAVE_DATA);
                         if (!block->IsValid(BLOCK_VALID_SCRIPTS)) {
                             if (fuzzed_data_provider.ConsumeBool()) { // Invalid

src/validation.cpp

@@ -5389,6 +5389,10 @@ void ChainstateManager::CheckBlockIndex()
         if (pindexFirstInvalid == nullptr) {
             // Checks for not-invalid blocks.
             assert((pindex->nStatus & BLOCK_FAILED_VALID) == 0); // The failed mask cannot be set for blocks without invalid parents.
+        } else {
+            // pindexFirstInvalid -> ...... -> pindex
+            // we check that descendants and block itself are BLOCK_FAILED_VALID
+            assert(pindex->nStatus & BLOCK_FAILED_VALID);
         }
         // Make sure m_chain_tx_count sum is correctly computed.
         if (!pindex->pprev) {