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Fix UB/data-race in RPCNotifyBlockChange
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ActiveTip() is *not* thread-safe, as the required ::cs_main lock will be
released as ActiveChainstate() returns.

ActiveTip() is an alias for ActiveChainstate().m_chain.Tip(), so m_chain
may be involved in a data-race (UB).
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MacroFake committed Aug 16, 2022
1 parent fa530bc commit fa97a52
Showing 1 changed file with 2 additions and 2 deletions.
4 changes: 2 additions & 2 deletions src/init.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -1751,12 +1751,12 @@ bool AppInitMain(NodeContext& node, interfaces::BlockAndHeaderTipInfo* tip_info)
// At this point, the RPC is "started", but still in warmup, which means it
// cannot yet be called. Before we make it callable, we need to make sure
// that the RPC's view of the best block is valid and consistent with
// ChainstateManager's ActiveTip.
// ChainstateManager's active tip.
//
// If we do not do this, RPC's view of the best block will be height=0 and
// hash=0x0. This will lead to erroroneous responses for things like
// waitforblockheight.
RPCNotifyBlockChange(chainman.ActiveTip());
RPCNotifyBlockChange(WITH_LOCK(chainman.GetMutex(), return chainman.ActiveTip()));
SetRPCWarmupFinished();

uiInterface.InitMessage(_("Done loading").translated);
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