index: prevent race by calling 'CustomInit' prior setting 'synced' flag

The 'm_synced' flag enables 'BlockConnected' events to be processed by
the index. If we set the flag before calling 'CustomInit', we could be
dispatching a block connected event to an uninitialized index child
class.

e.g. BlockFilterIndex, initializes the next filter position
inside 'CustomInit'. So, if `CustomInit` is not called prior receiving
the block event, the index will use 'next_filter_position=0' which
overwrites the first filter in disk.
This commit is contained in:
furszy 2023-05-22 12:51:15 -03:00
parent 22139f6e83
commit 3126454dcf
No known key found for this signature in database
GPG key ID: 5DD23CCC686AA623

View file

@ -103,15 +103,12 @@ bool BaseIndex::Init()
SetBestBlockIndex(locator_index);
}
// Note: this will latch to true immediately if the user starts up with an empty
// datadir and an index enabled. If this is the case, indexation will happen solely
// via `BlockConnected` signals until, possibly, the next restart.
m_synced = m_best_block_index.load() == active_chain.Tip();
// Skip pruning check if indexes are not ready to sync (because reindex-chainstate has wiped the chain).
if (!m_synced && g_indexes_ready_to_sync) {
const CBlockIndex* start_block = m_best_block_index.load();
bool synced = start_block == active_chain.Tip();
if (!synced && g_indexes_ready_to_sync) {
bool prune_violation = false;
if (!m_best_block_index) {
if (!start_block) {
// index is not built yet
// make sure we have all block data back to the genesis
prune_violation = m_chainstate->m_blockman.GetFirstStoredBlock(*active_chain.Tip()) != active_chain.Genesis();
@ -119,7 +116,7 @@ bool BaseIndex::Init()
// in case the index has a best block set and is not fully synced
// check if we have the required blocks to continue building the index
else {
const CBlockIndex* block_to_test = m_best_block_index.load();
const CBlockIndex* block_to_test = start_block;
if (!active_chain.Contains(block_to_test)) {
// if the bestblock is not part of the mainchain, find the fork
// and make sure we have all data down to the fork
@ -143,6 +140,16 @@ bool BaseIndex::Init()
return InitError(strprintf(Untranslated("%s best block of the index goes beyond pruned data. Please disable the index or reindex (which will download the whole blockchain again)"), GetName()));
}
}
// Child init
if (!CustomInit(start_block ? std::make_optional(interfaces::BlockKey{start_block->GetBlockHash(), start_block->nHeight}) : std::nullopt)) {
return false;
}
// Note: this will latch to true immediately if the user starts up with an empty
// datadir and an index enabled. If this is the case, indexation will happen solely
// via `BlockConnected` signals until, possibly, the next restart.
m_synced = synced;
return true;
}
@ -408,11 +415,6 @@ bool BaseIndex::Start()
RegisterValidationInterface(this);
if (!Init()) return false;
const CBlockIndex* index = m_best_block_index.load();
if (!CustomInit(index ? std::make_optional(interfaces::BlockKey{index->GetBlockHash(), index->nHeight}) : std::nullopt)) {
return false;
}
m_thread_sync = std::thread(&util::TraceThread, GetName(), [this] { ThreadSync(); });
return true;
}