Fix cs_main lock in LoadExternalBlockFile

When accessing mapBlockIndex cs_main must be held.

Author: promag

src/validation.cpp

@@ -4252,26 +4252,28 @@ bool LoadExternalBlockFile(const CChainParams& chainparams, FILE* fileIn, CDiskB
                 blkdat >> block;
                 nRewind = blkdat.GetPos();
 
-                // detect out of order blocks, and store them for later
                 uint256 hash = block.GetHash();
-                if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex.find(block.hashPrevBlock) == mapBlockIndex.end()) {
-                    LogPrint(BCLog::REINDEX, "%s: Out of order block %s, parent %s not known\n", __func__, hash.ToString(),
-                            block.hashPrevBlock.ToString());
-                    if (dbp)
-                        mapBlocksUnknownParent.insert(std::make_pair(block.hashPrevBlock, *dbp));
-                    continue;
-                }
-
-                // process in case the block isn't known yet
-                if (mapBlockIndex.count(hash) == 0 || (mapBlockIndex[hash]->nStatus & BLOCK_HAVE_DATA) == 0) {
+                {
                     LOCK(cs_main);
-                    CValidationState state;
-                    if (g_chainstate.AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr))
-                        nLoaded++;
-                    if (state.IsError())
-                        break;
-                } else if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex[hash]->nHeight % 1000 == 0) {
-                    LogPrint(BCLog::REINDEX, "Block Import: already had block %s at height %d\n", hash.ToString(), mapBlockIndex[hash]->nHeight);
+                    // detect out of order blocks, and store them for later
+                    if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex.find(block.hashPrevBlock) == mapBlockIndex.end()) {
+                        LogPrint(BCLog::REINDEX, "%s: Out of order block %s, parent %s not known\n", __func__, hash.ToString(),
+                                block.hashPrevBlock.ToString());
+                        if (dbp)
+                            mapBlocksUnknownParent.insert(std::make_pair(block.hashPrevBlock, *dbp));
+                        continue;
+                    }
+
+                    // process in case the block isn't known yet
+                    if (mapBlockIndex.count(hash) == 0 || (mapBlockIndex[hash]->nStatus & BLOCK_HAVE_DATA) == 0) {
+                        CValidationState state;
+                        if (g_chainstate.AcceptBlock(pblock, state, chainparams, nullptr, true, dbp, nullptr))
+                            nLoaded++;
+                        if (state.IsError())
+                            break;
+                    } else if (hash != chainparams.GetConsensus().hashGenesisBlock && mapBlockIndex[hash]->nHeight % 1000 == 0) {
+                        LogPrint(BCLog::REINDEX, "Block Import: already had block %s at height %d\n", hash.ToString(), mapBlockIndex[hash]->nHeight);
+                    }
                 }
 
                 // Activate the genesis block so normal node progress can continue