From 811d165458f8e068120a19ca79337b369ef8bbae Mon Sep 17 00:00:00 2001
From: Andronik Ordian <write@reusable.software>
Date: Wed, 4 Apr 2018 18:14:59 +0300
Subject: [PATCH] Validate if gas limit is not zero (#8307)

---
 ethcore/src/machine.rs   | 4 ++--
 json/src/spec/genesis.rs | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/ethcore/src/machine.rs b/ethcore/src/machine.rs
index ad36aa69d..fa6a62454 100644
--- a/ethcore/src/machine.rs
+++ b/ethcore/src/machine.rs
@@ -203,10 +203,11 @@ impl EthereumMachine {
 	/// The gas floor target must not be lower than the engine's minimum gas limit.
 	pub fn populate_from_parent(&self, header: &mut Header, parent: &Header, gas_floor_target: U256, gas_ceil_target: U256) {
 		header.set_difficulty(parent.difficulty().clone());
+		let gas_limit = parent.gas_limit().clone();
+		assert!(!gas_limit.is_zero(), "Gas limit should be > 0");
 
 		if let Some(ref ethash_params) = self.ethash_extensions {
 			let gas_limit = {
-				let gas_limit = parent.gas_limit().clone();
 				let bound_divisor = self.params().gas_limit_bound_divisor;
 				let lower_limit = gas_limit - gas_limit / bound_divisor + 1.into();
 				let upper_limit = gas_limit + gas_limit / bound_divisor - 1.into();
@@ -238,7 +239,6 @@ impl EthereumMachine {
 		}
 
 		header.set_gas_limit({
-			let gas_limit = parent.gas_limit().clone();
 			let bound_divisor = self.params().gas_limit_bound_divisor;
 			if gas_limit < gas_floor_target {
 				cmp::min(gas_floor_target, gas_limit + gas_limit / bound_divisor - 1.into())
diff --git a/json/src/spec/genesis.rs b/json/src/spec/genesis.rs
index 984053e77..f595e7750 100644
--- a/json/src/spec/genesis.rs
+++ b/json/src/spec/genesis.rs
@@ -16,7 +16,7 @@
 
 //! Spec genesis deserialization.
 
-use uint::Uint;
+use uint::{Uint, self};
 use hash::{Address, H256};
 use bytes::Bytes;
 use spec::Seal;
@@ -37,6 +37,7 @@ pub struct Genesis {
 	pub parent_hash: Option<H256>,
 	/// Gas limit.
 	#[serde(rename="gasLimit")]
+	#[serde(deserialize_with="uint::validate_non_zero")]
 	pub gas_limit: Uint,
 	/// Transactions root.
 	#[serde(rename="transactionsRoot")]