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

@@ -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