From 2cf31f5f2d5322f104d4c4748f09ef5e0ba96cd6 Mon Sep 17 00:00:00 2001
From: Robin Salen <30937548+Nashtare@users.noreply.github.com>
Date: Tue, 6 Jun 2023 09:39:36 +0200
Subject: [PATCH] Prevent shift ops from panicking (#1073)

---
 evm/src/witness/operation.rs | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/evm/src/witness/operation.rs b/evm/src/witness/operation.rs
index 5241c71b..1208c27f 100644
--- a/evm/src/witness/operation.rs
+++ b/evm/src/witness/operation.rs
@@ -468,7 +468,12 @@ pub(crate) fn generate_shl<F: Field>(
 ) -> Result<(), ProgramError> {
     let [(input0, log_in0), (input1, log_in1)] =
         stack_pop_with_log_and_fill::<2, _>(state, &mut row)?;
-    let result = input1 << input0;
+
+    let result = if input0 > U256::from(255u64) {
+        U256::zero()
+    } else {
+        input1 << input0
+    };
     append_shift(state, row, input0, log_in0, log_in1, result)
 }
 
@@ -478,7 +483,12 @@ pub(crate) fn generate_shr<F: Field>(
 ) -> Result<(), ProgramError> {
     let [(input0, log_in0), (input1, log_in1)] =
         stack_pop_with_log_and_fill::<2, _>(state, &mut row)?;
-    let result = input1 >> input0;
+
+    let result = if input0 > U256::from(255u64) {
+        U256::zero()
+    } else {
+        input1 >> input0
+    };
     append_shift(state, row, input0, log_in0, log_in1, result)
 }