From 106d196ec4a6451efedc60ab15957f231fa85639 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Tue, 21 Aug 2018 09:48:53 +0200
Subject: [PATCH] eth: ensure from<to when tracing chain (credits Chen Nan via
 bugbounty)

---
 eth/api_tracer.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/eth/api_tracer.go b/eth/api_tracer.go
index 722e2a6e3..704a6cdba 100644
--- a/eth/api_tracer.go
+++ b/eth/api_tracer.go
@@ -119,6 +119,9 @@ func (api *PrivateDebugAPI) TraceChain(ctx context.Context, start, end rpc.Block
 	if to == nil {
 		return nil, fmt.Errorf("end block #%d not found", end)
 	}
+	if from.Number().Cmp(to.Number()) >= 0 {
+		return nil, fmt.Errorf("end block (#%d) needs to come after start block (#%d)", end, start)
+	}
 	return api.traceChain(ctx, from, to, config)
 }