From eff424cc302152f3914e3f9c8b49efe92e33353f Mon Sep 17 00:00:00 2001
From: Sina M <1591639+s1na@users.noreply.github.com>
Date: Wed, 13 Mar 2024 07:40:02 +0100
Subject: [PATCH] eth/tracers: fix concurrency issue for JS-tracing a block
 (#29238)

This change fixes a concurrency-issue where JS-tracers were accessing the block-ctx GetHash function in a in parallel, which is not safe.
---
 eth/tracers/api.go | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/eth/tracers/api.go b/eth/tracers/api.go
index fa8c881d1a..0add06c8f6 100644
--- a/eth/tracers/api.go
+++ b/eth/tracers/api.go
@@ -632,7 +632,6 @@ func (api *API) traceBlockParallel(ctx context.Context, block *types.Block, stat
 	var (
 		txs       = block.Transactions()
 		blockHash = block.Hash()
-		blockCtx  = core.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)
 		signer    = types.MakeSigner(api.backend.ChainConfig(), block.Number(), block.Time())
 		results   = make([]*txTraceResult, len(txs))
 		pend      sync.WaitGroup
@@ -655,6 +654,11 @@ func (api *API) traceBlockParallel(ctx context.Context, block *types.Block, stat
 					TxIndex:     task.index,
 					TxHash:      txs[task.index].Hash(),
 				}
+				// Reconstruct the block context for each transaction
+				// as the GetHash function of BlockContext is not safe for
+				// concurrent use.
+				// See: https://github.com/ethereum/go-ethereum/issues/29114
+				blockCtx := core.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)
 				res, err := api.traceTx(ctx, msg, txctx, blockCtx, task.statedb, config)
 				if err != nil {
 					results[task.index] = &txTraceResult{TxHash: txs[task.index].Hash(), Error: err.Error()}
@@ -667,6 +671,7 @@ func (api *API) traceBlockParallel(ctx context.Context, block *types.Block, stat
 
 	// Feed the transactions into the tracers and return
 	var failed error
+	blockCtx := core.NewEVMBlockContext(block.Header(), api.chainContext(ctx), nil)
 txloop:
 	for i, tx := range txs {
 		// Send the trace task over for execution